This chapter thoroughly describes hard
disk installation. In particular, the chapter examines the
configuration, physical installation, and formatting of a hard
disk drive. This chapter also covers the basic procedures
necessary to install a hard disk drive into a PC system.
Hard Disk
Installation Procedures
To install a hard drive in an
IBM-compatible system, you must perform several procedures:
- Configure the drive
- Configure the controller or
interface
- Physically install the
drive
- Configure the system
- Low-level format the drive (not
required with IDE and SCSI)
- Partition the drive
- High-level format the drive
Drive configuration was discussed in
Chapter 15, "Hard Disk Interfaces." For complete configuration
information, consult the section that covers the type of drive
that you are installing.
The following sections describe the
other steps, which are simple to execute and, if done
properly, result in the successful installation of a bootable
hard disk. Special attention is given to issues of reliability
and data integrity to ensure that the installation is
long-lasting and trouble-free.
To begin the setup procedure, you need
to know several details about the hard disk drive, controller
or host adapter, and system ROM BIOS, as well as most of the
other devices in the system. This information usually appears
in the various OEM manuals that come with these devices. Make
sure when you purchase these items that the vendor includes
these manuals. (Many vendors do not include the manuals unless
you ask for them.) For most equipment sold today, you will get
enough documentation from the vendor or reseller of the
equipment to enable you to proceed.
If you are like me, however, and want
all the technical documentation on the device, you will want
to contact the original manufacturer of the device and order
the technical specification manual. For example, if you
purchase an IBM-compatible system that comes with a Western
Digital IDE hard disk, the seller probably will give you some
limited information on the drive, but not nearly the amount
that the actual Western Digital technical specification manual
provides. To get this documentation, you have to call Western
Digital and order it. The same goes for any of the other
components in most clones that are assembled rather than
manufactured. I find the OEM technical manuals to be essential
in providing the highest level of technical support
possible.
Here are a few of the major hard drive
vendors' Web sites:
http://www.maxtor.com
http://www.micropolis.com
http://www.conner.com/toc.shtml
http://www.wdc.com/welcome.html
Controller
Configuration
Configuring a disk controller involves
setting the different system resources that the controller
requires. Some controllers have these resources fixed, which
means that they cannot be altered. Other controllers provide
jumpers, switches, or even software that enable you to
reconfigure or change the resources used. Controllers with
adjustable resource settings often can be used in conjunction
with other controllers in a system, but controllers with fixed
resources usually cannot coexist with others.
All hard disk controllers and SCSI host
adapters require one or more of the following system
resources:
- ROM addresses
- DMA channel (DRQ)
- Interrupt Request Channel
(IRQ)
- I/O port addresses
Not all adapters use every one of these
resources, but some will use them all. In most cases, these
resources must be configured so that they are unique and
cannot be shared among several adapters. For example, if a
disk controller is using I/O port addresses from 1F0-1F7h, no
other device in the system can use those addresses.
When a conflict in resource use occurs,
not all of the adapters involved may function. In the case of
disk controllers, the controller will not function, and disk
access will be impossible or corrupted. You need to identify
which boards in the system have overlapping resources and then
change the configuration of one or more of those boards to
eliminate the conflict. Before installing a board, you should
know which resources the board will require, and you should
make sure that these resources are not being used by other
boards.
In most systems, this is a manual
procedure that requires you to know exactly what every adapter
in the system is using. If your system supports Plug and Play
(PnP), this will be much easier. On older MCA and EISA
systems, the procedure is also under software control. PnP
ISA, PCI, MCA, and EISA systems can automatically determine
whether two adapters use the same resource and then change the
configuration to eliminate the conflict.
For most systems, you need the
documentation for every adapter in the system to ensure that
no conflicts exist and to find out how to reconfigure a card
to eliminate a conflict. Software included with your system,
such as MSD (Microsoft Diagnostics, which comes with Windows
3.x and DOS 6.x) or the Device Manager in Windows 95, can help
when documentation is not available or is limited. Aftermarket
diagnostics and utility programs can also be helpful. Unless
your system conforms to the PnP specification, software will
normally not be able to identify direct conflicts, but if you
install one board at a time, they can identify the addresses
or resources that a given board is using.
Many system resources simply cannot be
identified by software alone. Several companies, including
AllMicro, Quarterdeck, Data Depot, and others manufacture
cards that can be used to monitor interrupt and DMA channels.
These boards are very helpful in identifying which of these
resources are used in your system. These companies and others
are listed in Appendix A.
NOTE: For more on software and
hardware diagnostic tools, see Chapter 21, "Software and
Hardware Diagnostic Tools." For additional information on
interrupts and DMA channels, see also Chapter 5, "Bus Slots
and I/O Cards."
ROM Addresses
Many disk controllers and SCSI host
adapters require an on-board BIOS to function. An on-board
BIOS can provide many functions, including:
- Low-level formatting
- Drive-type (parameter)
control
- Adapter configuration
- Support for nonstandard I/O port
addresses and interrupts
If the motherboard BIOS supports a hard
disk controller, an on-board BIOS is not needed--and in fact
is undesirable because it uses memory in the Upper Memory Area
(UMA). Fortunately, the on-board BIOS usually can be disabled
if it is not required.
Only controllers that meet certain
standards can run off the motherboard BIOS, including
ST-506/412 controllers, ESDI controllers, and IDE bus
adapters. These standards include the use of I/O port
addresses 170-17Fh and interrupt 14. If you are installing a
controller that uses other I/O port addresses or interrupt
settings (such as when adding a second controller to a
system), the motherboard BIOS will not be able to support it,
and an on-board BIOS will be required. XT controllers
universally need an on-board BIOS because the motherboard BIOS
has no hard disk support whatsoever.
SCSI adapters normally do not emulate
the WD1003-type disk interface and almost always require an
on-board BIOS to provide disk driver functions. This on-board
BIOS supports any of the adapter's settings; in most cases,
multiple SCSI host adapters can use the BIOS of the first
adapter, in which case the BIOSes on all but the first adapter
can be disabled.
If an on-board BIOS is required and
enabled, it will use specific memory address space in the UMA.
The UMA is the top 384K in the first megabyte of system
memory. The UMA is divided into three areas of two 64K
segments each, with the first and last areas being used by the
video-adapter circuits and the motherboard BIOS, respectively.
Segments C000h and D000h are reserved for use by adapter ROMs
such as those found on disk controllers or SCSI host adapters.
NOTE: You need to ensure that any
adapters using space in these segments do not overlap with
another adapter that uses this space. No two adapters can
share this memory space. Most adapters have jumpers,
switches, or even software that can adjust the configuration
of the board and change the addresses that are used to
prevent conflict.
Interrupt Request Channel
(IRQ)
All disk controllers and SCSI host
adapters require an interrupt line to gain the system's
attention. These devices invoke a hardware interrupt to gain
timely access to the system for data transfers and control.
The original 8-bit ISA systems have only eight interrupt
levels, with interrupts 2-7 available to any adapter. AT bus
(16-bit ISA), EISA, and MCA systems have 16 interrupt levels,
with interrupts 3-7, 9-12, and 14 and 15 available to any
adapter cards. IRQs 10-12 and 14 and 15 are 16-bit interrupts
available only to 16- or 32-bit adapters.
Tables 16.1 and 16.2 show the normally
used and normally available interrupts in ISA, EISA, and MCA
systems and in 8-bit ISA systems. The tables list the default
use for each interrupt and indicate whether the interrupt is
available in a bus slot.
Table 16.1 ISA, EISA, and
MCA Default Interrupt Assignments
IRQ |
Function |
Bus Slot |
0 |
System Timer |
No |
1 |
Keyboard Controller |
No |
2 |
Second IRQ Controller |
No |
8 |
Real-Time Clock |
No |
9 |
Network/Available (Redirected IRQ 2) |
Yes (8-bit) |
10 |
Available |
Yes (16-bit) |
11 |
SCSI/Available |
Yes (16-bit) |
12 |
Motherboard Mouse Port |
Yes (16-bit) |
13 |
Math Coprocessor |
No |
14 |
Hard Disk Controller |
Yes (16-bit) |
15 |
Secondary IDE |
Yes (16-bit) |
3 |
Serial Port 2 (COM2:) |
Yes (8-bit) |
4 |
Serial Port 1 (COM1:) |
Yes (8-bit) |
5 |
Sound/Parallel Port 2 (LPT2:) |
Yes (8-bit) |
6 |
Floppy Disk Controller |
Yes (8-bit) |
7 |
Parallel Port 1 (LPT1:) |
Yes (8-bit) |
Table 16.2 XT-Bus (8-Bit
ISA) Default Interrupt Assignments
IRQ |
Function |
Bus Slot |
0 |
System Timer |
No |
1 |
Keyboard Controller |
No |
2 |
Network/Available |
Yes (8-bit) |
3 |
Serial Port 2 (COM2:) |
Yes (8-bit) |
4 |
Serial Port 1 (COM1:) |
Yes (8-bit) |
5 |
Hard Disk Controller |
Yes (8-bit) |
6 |
Floppy Disk Controller |
Yes (8-bit) |
7 |
Parallel Port 1 (LPT1:) |
Yes (8-bit) |
Notice that some of the interrupts are
simply not available in slots; they are reserved for use only
by the indicated system function. Any interrupt that is listed
as being in use by an item that is not installed in your
system would be available. For example, if your system does
not have a motherboard mouse port, IRQ 12 would be available;
if your system does not have a second serial port, IRQ 3 would
be available.
You must discover which interrupts are
currently in use and which are currently available in a
system, and then configure any new cards to use only the
available interrupts. In a standard configuration, the hard
disk controller uses interrupt (IRQ) 14. Any secondary
controllers would have to use other interrupts. The standard
interrupt for a secondary controller is IRQ 15. If the system
does not support EIDE (Enhanced IDE) in the motherboard BIOS,
then any controllers that do not use IRQ 14 must have an
on-board BIOS to function. The older motherboard BIOS supports
disk controllers only at IRQ 14, whereas a BIOS with EIDE
support will run IDE ports at both IRQ 14 and 15. Most newer
systems have integral EIDE support and automatically include a
secondary IDE port, which is at IRQ 15.
Standard IDE adapters come
preconfigured for IRQ 14, which is fine if the adapter is the
only disk adapter in the system. Many SCSI host adapters, such
as the Adaptec 1540/1542C, come configured to one of the other
available 16-bit interrupts, such as IRQ 11. Old XT (8-bit)
hard disk controllers normally use IRQ 5.
DMA Channel
Direct Memory Access (DMA) is a
technique for transferring blocks of data directly into system
memory without the complete attention of the main processor.
The motherboard has DMA control circuits that orchestrate and
govern DMA transfers. In the original 8-bit XT bus, DMA was
the highest-performance transfer method, and XT hard disk
controllers universally used DMA channel 3 for high-speed
transfers.
In AT-Bus (16-bit ISA) systems, most
16-bit disk controllers and SCSI host adapters do not use a
DMA channel, partly because the performance of the AT Bus DMA
circuitry turned out to be very poor. Therefore, most adapters
use a technique called Programmed I/O (PIO), which
simply sends bytes of data through the I/O ports. PIO
transfers are faster than DMA transfers in most cases,
especially if the motherboard BIOS and device support
block-mode PIO, such as with the new IDE drives. If an adapter
does not use DMA, you can assume that PIO is used as the
data-transfer method and that no DMA channel is
required.
Some adapters have found a way around
the poor performance of the ISA bus by becoming what is known
as a bus master. A bus master actually takes control of
the bus and can override the DMA controller circuitry of the
motherboard to perform fast DMA transfers. These transfers can
exceed the performance of a PIO transfer (even block-mode
PIO), so you will find that many of the highest-performing
controllers have bus-master capabilities.
You have to select a DMA channel for
bus-master adapters to use. In an 8-bit ISA bus, normally only
DMA channel 1 is available; in a 16-bit ISA bus, however, DMA
channels 0-1, 3, and 5-7 are available. DMA channels 5-7 are
16-bit channels that most high-performance bus-master adapters
would want to use. XT disk controllers always use DMA channel
3, whereas most 16-bit AT or IDE controllers do not use DMA at
all. This is not a concern in the newer PCI bus
systems.
Tables 16.3 and 16.4 show the normally
used and normally available DMA channels. The tables list the
default use for each DMA channel and indicate whether the DMA
channel is available in a bus slot.
Table 16.3 16-Bit ISA
Default DMA Channel Assignments
DMA |
Function |
Transfer |
Bus Slot |
0 |
Available |
8-bit |
Yes(16-bit) |
1 |
Sound/Available |
8-bit |
Yes (8-bit) |
2 |
Floppy Disk Controller |
8-bit |
Yes (8-bit) |
3 |
ECP Parallel/Available |
8-bit |
Yes (8-bit) |
4 |
First DMA Controller |
N/A |
No |
5 |
Sound/Available |
16-bit |
Yes(16-bit) |
6 |
SCSI/Available |
16-bit |
Yes(16-bit) |
7 |
Available |
16-bit |
Yes(16-bit) |
Table 16.4 8-Bit ISA
Default DMA Channel Assignments
DMA |
Function |
Transfer |
Bus Slot |
0 |
Dynamic RAM Refresh |
N/A |
No |
1 |
Sound/Available |
8-bit |
Yes (8-bit) |
2 |
Floppy Disk Controller |
8-bit |
Yes (8-bit) |
3 |
Hard Disk Controller |
8-bit |
Yes (8-bit) |
Notice that some of the DMA channels
simply are not available in slots; they are reserved for use
only by the indicated system function. Any DMA channel that is
listed as being in use by an item that is not installed in
your system would be available. For example, if your 8-bit ISA
bus system does not have a hard disk controller, DMA channel 3
would be available.
PCI and EISA bus systems have
additional DMA capabilities that support even faster transfers
without the performance problems associated with
non-bus-master cards. The PCI and EISA buses also provide even
better support for bus-master devices that offer even higher
performance.
To configure an adapter that requires a
DMA channel, you first must find out which DMA channels
currently are in use and which channels are available in your
system. Unless you have an PCI or EISA system, software
techniques for determining this are very limited. Most
programs that claim to be capable of discovering which DMA
channels are being used are only reporting what any standard
configuration would be. In standard ISA systems, the only way
to know for sure is to check the documentation for each
adapter or to use a special hardware device that monitors DMA
transfers.
After determining what DMA channels are
free, you can set your adapter to any of those free channels.
DMA conflicts usually result in improper operation or
corrupted data transfers, so if you made a mistake, you
usually will know quickly.
PCI and EISA systems automatically set
up the boards so that no DMA conflicts exist. This method
works fully only in EISA systems with all EISA 32-bit adapters
installed. PCI buses usually have at least two or more ISA
slots that you still need to worry about.
I/O Port Addresses
I/O port addresses are like
mailboxes through which data and commands are sent to and from
an adapter. These addresses are different from memory
addresses. I/O ports must be used exclusively and cannot be
shared among different adapters. Each adapter usually uses a
group of sequential port addresses for communication with the
bus.
The standard I/O port addresses used by
disk controllers are 1F0-1F7h. These are the only addresses
that the motherboard BIOS supports, so if you have a disk
controller at any other port address, it must have an on-board
BIOS. Obviously, if you are adding a secondary controller to a
system, that controller must use different I/O addresses and
also must have an on-board BIOS. Most controllers use 170-177h
as secondary I/O addresses, which would be used if another
disk controller were in the system; however, you can use any
I/O addresses that are free.
I/O port conflicts are rare unless you
are installing multiple disk controllers in a system. In that
case, each controller needs different I/O port address
settings so as not to conflict with the others. To determine
what I/O ports are currently in use, you normally have to
refer to the documentation that comes with each device in your
system. Software normally cannot identify all used I/O port
addresses unless you have a PCI or EISA system. When port
conflicts exist, the devices in conflict do not function, or
they function improperly.
Multi-Function I/O
CardsMulti-function I/O cards are a combination floppy
disk, hard disk, and serial and parallel port adapters all
on one expansion card. Most newer motherboards have all
these functions built right into the motherboard, but you
may see a few of these multi-function boards in older PCI or
VLB systems, and it is important to note that you will have
to disable the hard disk controller on this board before
installing a new controller.
Physical
Installation
The procedure for physical installation
of a hard disk is much the same as the procedure for
installing a floppy drive. You must have the correct screws,
brackets, and faceplates for the specific drive and system
before you can install the drive.
Some AT or Baby-AT type computer cases
require plastic rails that are secured to the sides of the
drives so that they can slide into the proper place in the
system (see Figure 16.1). Compaq uses a different type of
rail, as does Hewlett-Packard, Packard Bell, and so on. When
you purchase a drive, the vendor usually includes the
"Standard-type" rails, so be sure to specify whether you need
the special manufacturer type. IBM PC-type and XT-type systems
do not need rails, but they may need a bracket to enable
double-stacking of half-height drives. Several companies
listed in Appendix B specialize in drive-mounting brackets,
cables, and other hardware accessories. Also, many newer after
market computer cases have eliminated the need for drive rails
all together by making the expansion slot itself to the 3 1/2-
or 5 1/4-inch drive specification, allowing you to bolt the
new drive directly to the case itself.
NOTE: You should also note the
length of the cable itself. In some cases, the drive cable
is not long enough to reach the new drive location. You can
try to reposition the original drive if you have the
available expansion slots, or just get a longer cable.
Different faceplate, or bezel, options
are available; make sure that you have the correct bezel for
your application. Some systems, for example, do not need a
bezel; if a bezel is on the drive, it must be removed. If you
are installing a half-height drive in a full-height bay, you
may need a blank half-height bezel to fill the hole, or you
may want to order a half-height drive with a full-height bezel
so that no hole is created. Several vendors listed in Appendix
A sell a variety of drive mounting kits, hardware, rails,
adapters, and cables.
FIG.
16.1 A full-height hard disk with AT
mounting rails.
CAUTION: Make sure you use only
the screws that come with your new drive. Many drives come
with a special short-length screw that can have the same
thread as other screws you might use in your system, but the
shorter screws will not drive too far into the drive, which
could cause problems.
System
Configuration
When the drive is physically installed,
you can begin configuring the system to the drive. You have to
tell the system about the drive so that the system can boot
from it when it powered on. How you set and store this
information depends on the type of drive and system you have.
Standard (IDE) setup procedures are used for most hard disks
except SCSI drives. SCSI drives normally follow a custom setup
procedure that varies depending on the host adapter that you
are using. If you have SCSI drives, follow the instructions
included with the host adapter to configure the
drives.
Automatic Drive
Typing
If the system is an AT type and you are
using the mother-board BIOS to support the hard disks, you
need to know some information about the BIOS, such as what
drives are supported in the hard drive table. Many BIOS
versions now have user-definable drive types that enable you
to enter any set of parameters required to match your drive.
For IDE drives, all new BIOS versions have automatic typing,
which interrogates the drive and automatically enters the
parameter information returned by the drive. This procedure
eliminates errors or confusion in parameter
selection.
If you are dealing with an older
motherboard that does not support automatic typing, the
information about the drive table appears in the technical
manuals provided with the motherboard or the BIOS. Appendix A
includes a list of drive types for many different BIOS
versions. For systems that are not listed, you can find this
information in the system's technical reference manual. Often,
the BIOS setup program shows you all the available selections
on-screen, enabling you to select the best choice
interactively and eliminating the need to research this
information.
Manual Drive Typing
After you collect the necessary
information, the next step is to tell the system what kind of
drive is attached so that the system can boot from the drive
(eventually). This chapter discusses the installation of an
example drive in an AT-type and ATX-type of system. With
knowledge of drive interfacing, you can install just about any
drive in any system.
First, you need to read the drive
manual and locate the required information. The manual for
this example contains the following drive-parameter
information:
- 918 cylinders
- 15 heads
- 17 or 26 sectors per track (MFM or
RLL encoding)
- No write precompensation
required
- Seven defective tracks: (specific to
each drive)
Cyl 188, Head 7 |
Cyl 601, Head 13 |
Cyl 217, Head 5 |
Cyl 798, Head 10 |
Cyl 218, Head 5 |
Cyl 835, Head 5 |
Cyl 219, Head 5 |
|
To install this drive in an AT-type
case, I could simply use the original IDE drive; however, I
would have to live with the relatively slow performance that
this controller provides. A better choice is to upgrade the
controller with an EIDE PIO mode 4 controller. This controller
not only supports up to four IDE devices including CD-ROM, but
will provide me with up to 16.6M/sec transfer rate.
NOTE: For more information on
installation and configuration of drive controllers, see
Chapter 15, "Hard Disk Interfaces."
The example controller uses PIO
transfers and does not require a DMA channel for the hard disk
controller portion. Because this controller also contains a
floppy controller, some additional information specific to the
floppy controller portion of the card is required:
- Interrupt Request Channel (IRQ) =
6
- DMA channel (DRQ) = 2
- I/O ports = 3F0-3F7
You need some of this information to
ensure that the card is uniquely configured compared with
other cards in the system. The system cannot have other cards
using the same IRQ, DMA, ROM, or I/O ports as this card. Keep
this information for future reference, and cross-check for
conflicts when you add other cards to the system. The step
pulse rates and interleave information are all that you need
to comple ete the setup.
After you find the information about
the drive and controller, you need to match the drive's
parameters to one of the drive-table entries in the
motherboard ROM. ROM drive tables for IBM and many other
compatible systems are listed in Appendix A, which also
includes a detailed list of a large number of hard disk drives
with parameter specifications. The information in Appendix A
saved me several times when the original manuals were nowhere
to be found. However, most drive tables are now embedded in
the CMOS of the motherboard, and usually you have to choose
User Defined (if you don't have an Auto-Configure option)
option anyway, and fill in your new drive's parameters because
most new drives are much larger than any of the
available drive type choices.
TIP: The landing-cylinder
designation is superfluous because all new drives
automatically park and lock their heads at power-down,
although it would be used if you ever ran a correctly
written head-parking program.
This type of drive-table information
does not apply to IBM ESDI or SCSI hard disk controllers, host
adapters, and drives. Because ESDI and SCSI controllers and
host adapters query the drive directly for the required
parameters, no table-entry selection is necessary. The table
for ST-506/412 drives, however, still appears in the ROM BIOS
of most PS/2 systems, even if the model came standard with the
ESDI or SCSI disk subsystem.
The manufacturers of most compatibles
have enhanced the motherboard ROM BIOS tables in three ways:
- Additional types. The first
thing that the manufacturers did was add more drive types to
the table. Because the table had room for 47 or more
entries, many compatible BIOS versions simply filled out all
the entries with values that matched the most popular drives
on the market, generally making drive installations easier.
IBM tables often were short of the maximum number of
possible entries.
- User-definable drive types.
Most makers of compatibles then added a user- definable
type, which used unused areas of the CMOS memory to store
all the drive-parameter information. This was an excellent
solution, because during setup you can type a parameter that
matches any drive on the market. The only drawback is that
if the CMOS battery dies or the saved values are corrupted
in some way, you would have to re-enter the information
exactly as it was before to regain access to the drive. Many
people did not write down the parameters that they used, or
they used improper parameters that caused
problems.
- Automatic detection. Most of
the newer BIOS versions include a feature that is specific
to IDE drives. Because most IDE drives are intelligent and
will respond to a command called Identify Drive,
the BIOS sends this command to the drive, which then
responds with the correct parameters. This feature
eliminates the need to type the parameters because the BIOS
will accept what the drive tells it.
As mentioned earlier, most of the newer
compatible BIOS versions have both the user-definable type
feature and automatic determination for IDE drives.
ROM Replacement
One way around the drive-table limits
is to purchase and install a new ROM BIOS. A Phoenix ROM BIOS
set, for example, costs about $50. These ROMs include a
user-definable drive-type setting, which is the most elegant
solution to this problem. A new set of ROMs probably will give
you additional features, such as a built-in setup program,
support for HD or ED 3 1/2-inch floppy drives, and Enhanced
Keyboard support.
RLL/ESDI System
Configuration
RLL and ESDI drives usually are not
represented in the internal drive tables of older BIOS
versions. Consequently, the controllers for these drives often
have an on-board ROM BIOS that either contains an internal
list of choices for the interface or enables you to
dynamically configure (define) the controller to the specific
geometry of the drive.
If you have a motherboard BIOS with a
user-defined drive type (recommended), you can simply enter
the correct parameters and the drive will be supported.
(Remember to write down the parameters that you use; if you
lose them, you can lose access to the drive if you don't
re-enter the parameters properly.) When using a user-definable
type, you can disable the controller BIOS.
IDE System
Configuration
Intelligent IDE drives can use the
geometry that represents their true physical parameters, or
they can translate to other drive geometries that have the
same number of sectors or fewer. Simply select a type, or
enter a user-definable type that is less than or equal to the
total capacity of the drive.
SCSI System
Configuration
Almost all SCSI drives use DRIVE
TYPE 0 or NONE, because the host adapter BIOS
and the drive communicate to establish the drive geometry. The
low-level formatting routines usually are accessed on the host
adapter through a configuration, setup, and format program.
All SCSI drives are low-level formatted at the factory.
Formatting and
Software Installation
Proper setup and formatting are
critical to a drive's performance and reliability. This
section describes the procedures used to format a hard disk
drive correctly. Use these procedures when you install a new
drive in a system or immediately after you recover data from a
hard disk that has been exhibiting problems.
Three major steps complete the
formatting process for a hard disk drive subsystem:
- Low-level formatting
- Partitioning
- High-level formatting
Considerations Before Low-Level
Formatting
In a low-level format (LLF),
which is a "real" format, the tracks and sectors of the disk
are outlined and written. During the LLF, data is written
across the entire disk. An improper LLF results in lost data
and in many read and write failures. You need to consider
several things before initiating an LLF.
Data Backup
Low-level formatting is the primary
standard repair procedure for hard disk drives that are having
problems. Because data values are copied to the drive at every
possible location during an LLF, necessary data-recovery
operations must be performed before an LLF operation.
CAUTION: After an LLF has been
performed, you cannot recover any information previously
written to the drive.
Because an LLF overwrites all the data
on a drive, it is a good way to erase an entire drive if you
are trying to ensure that nobody will be able to get data from
it. Government standards for this type of procedure actually
require the data to be overwritten several times with
different patterns, but for most intents and purposes, if the
drive is overwritten one time, nobody will be able to read any
data that was on it.
System Temperature
Sector header and trailer information
is written or updated only during the LLF operation. During
normal read and write activity, only the 512 bytes plus the
CRC (Cyclic Redundancy Check) bytes in the trailer are written
in a sector. Temperature-induced dimensional changes in the
drive platters during read and write operations can become a
problem.
When a 5 1/4-inch platter drive is
low-level formatted five minutes after powerup at a relatively
cold platter temperature of 70° F, the sector headers and
trailers and the 512-byte dummy data values are written to
each track on each platter at specific locations.
Suppose that you save a file on a drive
that has been running for several hours at a platter
temperature of 140° F. The data areas of only several sectors
are updated. But with the drive platters as much as 70° warmer
than when the drive was formatted, each aluminum drive platter
will have expanded in size by 2.5 thousandths of an inch
(taking into account the coefficient of linear thermal
expansion of aluminum). Each track, therefore, would have
moved outward a distance of approximately 1.25 thousandths of
an inch. Most 5 1/4-inch hard disks have track densities
between 500 and 1,000 TPI (tracks per inch), with distances of
only 1 to 2 thousandths of an inch between adjacent tracks. As
a result, the thermal expansion of a typical 5 1/4-inch hard
disk platter could cause the tracks to migrate from one-half
to more than one full track of distance below the heads. If
the drive head-movement mechanism does not compensate for
these thermally induced dimensional changes in the platters,
severe mistracking results.
When mistracking occurs, the data areas
in each sector that have been updated at the higher
temperature fail to line up with the sector header and trailer
information. If the sector header and trailer information
cannot be read properly, DOS usually issues an error message
like this one: Sector not found reading drive C
Abort, Retry, Ignore, Fail?
The data is misaligned with the sector
boundaries on those tracks. This thermal effect also can work
in reverse: If the drive is formatted and written to while it
is extremely hot, it may not read properly while cold because
of dimensional changes in the platters. This problem occurs
with drives that have the "Monday-morning blues," in which
they spin but cannot read data properly when they are first
powered on, especially after being off for an extended period
(over a weekend, for example). If you leave the power to the
system on for some time so that the drive can warm up, the
system then may boot and run normally.
If this happens, the next step is to
back up the drive completely and initiate a new LLF at the
proper operating temperature (described next). This procedure
enables the drive to work normally again until
temperature-induced mistracking becomes great enough to cause
the problem again.
Knowing that temperature fluctuations
can cause mistracking, you should understand the reasons for
the following basic rules of disk use:
- Leave the system's power on for at
least 30 minutes before performing an LLF on its hard disk.
This step ensures that the platters are at a normal
operating temperature and have stabilized
dimensionally.
- If possible, allow a system some
time to warm up after power-on before storing any data on
the hard disk. This procedure is not required for voice coil
drives.
If you have a cheap stepper motor drive
that consistently exhibits temperature-related mistracking
problems, you may want to consider running the drive
constantly. Doing so would extend its trouble-free life span
significantly because the temperature and dimensions of the
platters would stay relatively constant.
These kinds of temperature-fluctuation
problems are more of a problem with drives that have open-loop
stepper motor actuators (which offer no thermal compensation)
than with the closed-loop voice coil actuators (which follow
temperature-induced track migration and compensate completely,
resulting in no tracking errors even with large changes in
platter dimensions).
Modern voice coil actuator drives do
not exhibit these dimensional instabilities due to thermal
expansion and contraction of the platters because they have a
track-following servo mechanism. As the tracks move, the
positioner automatically compensates. Many of these drives
undergo a noticeable thermal compensation sequence every five
minutes or so for the first 30 minutes after being powered on,
and usually every 30 minutes after that. During these
thermal-compensation routines, you hear the heads move back
and forth as they measure and compensate for platter-dimension
changes.
Drive Operating
Position
Another consideration before formatting
a drive is ensuring that the drive is formatted in the
operating position it will have when it is installed in the
system. Gravity can place on the head actuator different loads
that can cause mistracking if the drive changes between a
vertical and a horizontal position. This effect is minimized
or even eliminated in most voice coil drives, but this
procedure cannot hurt.
Additionally, drives that are not
properly shock-mounted should be formatted only when they are
installed in the system because the installation screws exert
twisting forces on the drive's Head Disk Assembly (HDA), which
can cause mistracking. If you format the drive with the
mounting screws installed tightly, it may not read with the
screws out, and vice versa. Be careful not to overtighten the
mounting screws, because doing so can stress the HDA. This
usually is not a problem if the drive's HDA is isolated from
the frame by rubber bushings.
In summary, for a proper LLF, the drive
should be
- At a normal operating
temperature
- In a normal operating
position
- Mounted in the host system (if the
drive HDA is not shock-mounted or isolated from the drive
frame by rubber bushings)
Because many different makes and models
of controllers differ in the way that they write data to a
drive, especially with respect to the encoding scheme, it is
best to format the drive using the same make and model of
controller as the controller that will be used in the host
system. Some brands of controllers work exactly alike,
however, so this is not an absolute requirement even if the
interface is the same. This problem does not occur with IDE or
SCSI drives, of course, because the controller is built into
the drive. Usually, if the controller establishes the drive
type by using its own on-board ROM rather than the system
setup program, it will be incompatible with other
controllers.
Low-Level Format
Of these procedures, the LLF is most
important to ensure trouble-free operation of the drive. This
format is the most critical of the operations and must be done
correctly for the drive to work properly. The LLF includes
several subprocedures:
- Scanning for existing defect
mapping
- Selecting the
interleave
- Formatting and marking (or
remarking) manufacturer defects
- Running a surface analysis
On all new systems, these subprocedures
are performed automatically by the system's LLF program and
require no user intervention, and you need not continue in
this section. On older systems, you must take the initiative,
and should read on.
To perform the drive defect mapping, to
select an interleave, and to complete a surface analysis of
the drive, you need information about the drive, the
controller, and possibly the system. This information usually
is provided in separate manuals or documents for each item;
therefore, be sure that you get the complete documentation for
your drive and controller products when you purchase them. The
specific information required depends on the type of system,
controller, and LLF program that you are using.
Defect Mapping
Before formatting the disk, you need to
know whether the drive has defects that have to be mapped out.
Older drives came with a list of defects discovered by the
manufacturer during the drive's final quality control testing.
These defects were marked so that they are not used later to
store programs or data.
Defect mapping was one of the most
critical aspects of low-level formatting, now just a
historical curiosity as low-level formatting is now done
almost exclusively by the manufacturer. If you would like to
understand the defect-mapping procedures, you first must
understand what happens when a defect is mapped on a
drive.
The manufacturer's defect list usually
indicated defects by cylinder and track. When this information
is entered, an LLF program marked these tracks with invalid
checksum figures in the header of each of the sectors,
ensuring that nothing can read or write to these locations.
When DOS performed a high-level format of the disk, the DOS
FORMAT program could not read these locations, and it marked
the involved clusters in the File Allocation Table (FAT) so
that they never will be used.
The list of defects that the
manufacturer gives you probably is more extensive than what a
program could determine from your system, because the
manufacturer's test equipment is far more sensitive than a
regular disk controller. The FORMAT program did not find the
defects automatically; you probably had to enter them
manually. The exceptions are new systems, in which the defect
list is encoded in a special area of the drive that normal
software cannot access. The LLF program (included in the
motherboard BIOS program that comes with the systems) reads
this special map, thereby eliminating the need to enter these
locations manually.
TIP: If your motherboard BIOS
does not have an LLF utility built in, you are probably
better off not low-level formatting an IDE drive.
All new drives are low-level formatted
by the manufacturer. If you bought a system with a drive
already installed by the manufacturer or dealer, an LLF
probably was done for you. Most manufacturers no longer
recommend you LLF any IDE type drive.
Although an actual defect is
technically different from a marked defect, these defects
should correspond to one another if the drive is formatted
properly. For example, I can enter the location of a good
track into the LLF program as a defective track. The LLF
program then corrupts the checksum values for the sectors on
that track, rendering them unreadable and unwriteable. When
the DOS FORMAT program encounters that track, it finds the
track unreadable and marks the clusters occupying that track
as being bad. After that, as the drive is used, DOS ensures
that no data ever is written to that track. The drive stays in
that condition until you redo the LLF of that track, indicate
that the track is not to be marked defective, and redo the
high-level format that no longer will find the track
unreadable and therefore permit those clusters to be used. In
general, unless an area is marked as defective in the LLF, it
will not be found as defective by the high-level format, and
DOS will subsequently use it for data storage.
Defect mapping becomes a problem when
someone formats a hard disk and fails to enter the
manufacturer's defect list, which contains actual defect
locations, so that the LLF can establish these tracks or
sectors as marked defects. Letting a defect go unmarked will
cost you data when the area is used to store a file that you
subsequently cannot retrieve.
Unfortunately, the LLF program does not
automatically find and mark any areas on a disk that are
defective. The manufacturer's defect list is produced by very
sensitive test equipment that tests the drive at an analog
level. Most manufacturers indicate areas as being defective
even if they are just marginal. The problem is that a marginal
area today may be totally unreadable in the future. You should
avoid any area suspected as being defective by entering the
location during the LLF so that the area is marked; then DOS
is forced to avoid the area.
Currently Marked Defects
Scan
Most LLF programs have the capability
to perform a scan for previously marked defects on a drive.
Some programs call this operation a defect scan; IBM
calls it Read Verify in the IBM Advanced Diagnostics.
This type of operation is nondestructive and reports by
cylinder and head position all track locations marked bad. Do
not mistake this for a true scan for defective tracks on a
disk, which is a destructive operation normally called a
surface analysis (discussed in the section "Surface Analysis"
later in this chapter). If a drive was low-level formatted
previously, you should scan the disk for previously marked
defects before running a fresh LLF for several reasons:
- To ensure that the previous LLF
correctly marked all manufacturer-listed defects.
Compare the report of the defect scan with the
manufacturer's list, and note any discrepancies. Any defects
on the manufacturer's list that were not found by the defect
scan were not marked properly.
- To look for tracks that are
marked as defective but are not on the manufacturer's
list. These tracks may have been added by a previously
run surface-analysis program (in which case they should be
retained), or they may result from the previous formatter's
typographical errors in marking the manufacturer's defect.
One of my drive manufacturer's lists showed Cylinder 514
Head 14 as defective. A defect scan, however, showed that
track as good but Cylinder 814, Head 14 as bad. Because the
latter location was not on the manufacturer's list, and
because typing 5 instead of 8 would be an easy
mistake to make, I concluded that a typographical error was
the cause and then reformatted the drive, marking Cylinder
514, Head 14 as bad and enabling Cylinder, 814 Head 14 to be
formatted as a good track, thus "unmarking" it.
If you run a surface analysis and
encounter defects in addition to those on the manufacturer's
list, you can do one of two things:
- If the drive is under warranty,
consider returning it.
- If the drive is out of warranty,
grab a pen and write on the defect-list sticker, adding the
bad tracks discovered by the surface-analysis program. (The
low-level formatter built into the system BIOS performs a
surface analysis immediately after the LLF; if it discovers
additional defects, it automatically adds them to the defect
list recorded on the drive.) Adding new defects to the
sticker in this manner means that these areas are not
forgotten when the drive is subsequently reformatted.
Manufacturer's Defect
List
The manufacturer tests a new hard disk
by using sophisticated analog test instruments that perform an
extensive analysis of the surface of the platters. This kind
of testing can indicate the functionality of an area of the
disk with great accuracy, precisely measuring information such
as the signal-to-noise ratio and recording
accuracy.
Some manufacturers have more demanding
standards than others about what they consider to be defects.
Many people are bothered by the fact that when they purchase a
new drive, it comes with a list of defective locations; some
even demand that the seller install a defect-free drive. The
seller can satisfy this request by substituting a drive made
by a company with less-stringent quality control, but the
drive will be of poorer quality. The manufacturer that
produces drives with more listed defects usually has a
higher-quality product because the number of listed defects
depends on the level of quality control. What constitutes a
defect depends on who is interpreting the test
results.
To mark the manufacturer defects listed
for the drive, consult the documentation for your LLF program.
For most drives, the manufacturer's defect list shows the
defects by cylinder and head; other lists locate the defect
down to the bit on the track that is bad, starting with the
index location.
CAUTION: Make sure that all
manufacturer's defects have been entered before proceeding
with the LLF.
Some systems automatically mark the
manufacturer's defects, using a special defect file recorded
on the drive by the manufacturer. For such a system, you need
a special LLF program that knows how to find and read this
file. Automatic defect-map entry is standard for IBM PS/2
systems and for most ESDI and all SCSI systems. Consult the
drive or controller vendor for the proper LLF program and
defect-handling procedures for your drive.
NOTE: Data recovery utilities
such as ScanDisk (DOS/Windows) or Norton Utilities cannot
mark the sectors or tracks at the physical format level. The
bad cluster marks that they make are stored only in the FAT
and are easily erased during the next high-level format
operation. You should also use an LLF utility designed for
your drive (contact the manufacturer), which will properly
mark bad sectors and assign spares at the physical disk
level.
Surface Analysis
A defect scan is a scan for marked
defects; a surface analysis is a scan for actual
defects. A surface analysis ignores tracks already marked
defective by an LLF and tests the unmarked tracks. The
surface-analysis program writes 512 bytes to each sector on
the good tracks, reads the sectors back, and compares the data
read to what was written. If the data does not verify, the
program (like an LLF) marks the track bad by corrupting the
checksum values for each sector on that track. A proper
surface analysis is like an LLF program in that it should
bypass the DOS and the BIOS so that it can turn off controller
retry operations and also see when ECC (Error Correction Code)
is invoked to correct soft errors.
Surface-analysis programs are
destructive: They write over every sector except those that
already are marked as bad. You should run a surface-analysis
program immediately after running an LLF to determine whether
defects have appeared in addition to the manu-facturer's
defects entered during the LLF. A defect scan after the LLF
and the surface analysis shows the cumulative tracks that were
marked bad by both programs.
If you have lost the manufacturer's
defect list, you can use the surface-analysis program to
indicate which tracks are bad, but this program never can
duplicate the accuracy or sensitivity of the original
manufacturer testing.
Although it is recommended if you have
been experiencing any problems with a drive, on new drives I
normally do not run a surface analysis after low-level
formatting for several reasons:
- Compared with formatting, surface
analysis takes a long time. Most surface-analysis programs
take two to five times longer than an LLF. An LLF of a 120M
drive takes about 15 minutes; a surface analysis of the same
drive takes an hour or more. Moreover, if you increase the
accuracy of the surface analysis by allowing multiple passes
or multiple patterns, the surface analysis takes even
longer.
- With high-quality drives, I never
find defects beyond those that the manufacturer specified.
In fact, the surface-analysis programs do not find all the
manufacturer's defects if I do not enter them manually.
Because the high-quality (voice coil) drives that I use have
been tested by the manufacturer to a greater degree than a
program can perform on my system, I simply mark all the
defects from the manufacturer's list in the LLF. If I were
using a low-quality (stepper motor) drive or installing a
used and out-of-warranty drive, I would consider performing
a surface analysis after the LLF.
Why Low-Level Format?
Even though it generally is not
necessary (or even recommended) to LLF IDE or SCSI drives,
there are a few good reasons to consider an LLF. One reason is
that an LLF will wipe out all the data on a drive, ensuring
that other people will not be able to read or recover that
data. This procedure is useful if you are selling a system and
do not want your data to be readable by the purchaser. Another
reason for wiping all the data from a drive is to remove
corrupted or non-DOS operating-system partitions and even
virus infections. The best reason is for defect management. As
you may have noticed, most ATA-IDE drives appear to have no
"bytes in bad sectors" under CHKDSK or any other
software.
Any defects that were present on the
drive after manufacturing were reallocated by the factory LLF.
Essentially, any known bad sectors are replaced by spare
sectors stored in different parts of the drive. If any new
defects occur, such as from a minor head/platter contact or
drive mishandling, a proper IDE-aware LLF program can map the
new bad sectors to other spares, hiding them and restoring the
drive to what appears to be defect-free status.
Because the IDE (ATA) specification is
an extension of the IBM/WD ST-506/412 controller interface,
the specification includes several new CCB commands that were
not part of the original INT 13h/CCB support. Some of these
new CCB commands are vendor-specific and are unique to each
IDE drive manufacturer. Some manufacturers use these special
CCB commands for tasks such as rewriting the sector headers to
flag bad sectors, which in essence means LLF. When using these
commands, the drive controller can rewrite the sector headers
and data areas and then carefully step over any servo
information (if the drive uses an embedded servo).
IDE drives can be low-level formatted,
although some drives require special vendor- specific commands
to activate certain LLF features and defect-management
options. Seagate, Western Digital, Maxtor, IBM, and others
make specific LLF and spare-sector defect-management software
specific to their respective IDE drives. Conner drives are
unique in that to actually LLF them, you need a special
hardware device that attaches to a diagnostic port connector
on the Conner IDE drive. A company called TCE (they are in the
vendor list in Appendix A) sells such a device for $99.
Coincidentally, this device is called The Conner. It includes
software and the special adapter device that permits true
low-level formatting (including rewriting all sectors and
sector headers, as well as completely managing spare sector
defects) at the factory level.
Other companies have developed LLF
software that recognizes the particular IDE drive and uses the
correct vendor-specific commands for the LLF and defect
mapping. The best of these programs is Ontrack's Disk Manager.
A general-purpose diagnostic program that also supports
IDE-drive formatting is the MicroScope package by Micro
2000.
Intelligent IDE drives must be in
nontranslating, or native, mode to LLF them. Zoned
Recording drives can perform only a partial LLF, in which the
defect map is updated and new defective sectors can be marked
or spared, but the sector headers usually are rewritten only
partially, and only for the purpose of defect mapping. In any
case, you are writing to some of the sector headers in one
form, and physical (sector-level) defect mapping and sector
sparing can be performed. This procedure is, by any standard
definition, an LLF.
On an embedded servo drive, all the
servo data for a track is recorded at the same time by a
specialized (usually laser-guided) servowriter. This servo
information is used to update the head position continuously
during drive function, so that the drive automatically
compensates for thermal effects. As a result, all the
individual servo bursts are in line on the track. Because the
servo controls head position, there is no appreciable
head-to-sector drift, as there could be on a nonservo
drive.
This is why even though it is possible
to LLF embedded servo drives, it rarely is necessary. The only
purpose for performing an LLF on an embedded servo drive is to
perform additional physical- (sector-) level defect mapping or
sector sparing for the purpose of managing defects that occur
after manufacture. Because no drift occurs, when a sector is
found to contain a flaw, it should remain permanently marked
bad; a physical flaw cannot be repaired by
reformatting.
Most IDE drives have three to four
spare sectors for each physical cylinder of the drive. These
hundreds of spare sectors are more than enough to accommodate
the original defects and any subsequent defects. If more
sectors are required, the drive likely has serious physical
problems that cannot be fixed by software.
Software for Low-Level
Formatting
You often can choose among several
types of LLF programs, but no single LLF program works on all
drives or all systems. Because LLF programs must operate very
closely with the controller, they often are specific to a
controller or controller type. Therefore, ask the controller
manufacturer for the formatting software it
recommends.
If the controller manufacturer supplies
an LLF program (usually in the controller's ROM), use that
program, because it is the one most specifically designed for
your system and controller. The manufacturer's program can
take advantage of special defect-mapping features, for
example. A different format program not only might fail to use
a manufacturer-written defect map, but also might overwrite
and destroy it.
For a general-purpose ST-506/412, ESDI,
or IDE LLF program, I recommend the Disk Manager program by
Ontrack. For the ST-506/412 interface only, I recommend the
IBM Advanced Diagnostics or the HDtest program by Jim
Bracking, a user-supported product found on many electronic
bulletin boards, including CompuServe. (These companies are
listed in the vendor list at the back of this book.) For SCSI
systems and systems on which the other recommended programs do
not work, you normally use will the format program supplied
with the SCSI host adapter.
How Low-Level Format Software
Works
There are several ways that a program
can LLF a drive. The simplest way is to call the BIOS by using
INT 13h functions such as the INT 13h, function 05h
(Format Track) command. The BIOS then converts this
command to what is called a CCB (Command Control Block)
command: A block of bytes sent from the proper I/O ports
directly to the disk controller. In this example, the BIOS
would take INT 13h, 05h and convert it to a CCB
50h (Format Track) command, which would be sent
through the Command Register Port (I/O address 1F7h for
ST-506/412 or IDE). When the controller receives the CCB
Format Track command, it may actually format the
track or may simply fill the data areas of each sector on the
track with a predetermined pattern.
The best way to LLF a drive is to
bypass the ROM BIOS and send the CCB commands directly to the
controller. Probably the greatest benefit in sending commands
directly to the drive controller is being able to correctly
flag defective sectors via the CCB Format Track
command, including the capability to perform sector sparing.
This is why IDE drives that are properly low-level formatted
never show any bad sectors.
By using the CCB commands, you also
gain the ability to read the Command Status and Error
registers (which enable you to detect things such as ECC
corrected data, which is masked by DOS INT 13h). You
also can detect whether a sector was marked bad by the
manufacturer or during a previous LLF and can maintain those
marks in any subsequent Format Track commands,
thereby preserving the defect list. I do not recommend
unmarking a sector (returning it to "good" status), especially
if the manufacturer previously marked it as bad.
When you use CCB commands, you can read
and write sector(s) with automatic retries as well as ECC
turned off. This capability is essential for any good surface
analysis or LLF program, and this is why I recommend programs
that use the CCB hardware interface rather than the DOS INT
13h interface.
Ontrack Disk Manager
For AT-type systems and other systems
with controllers that do not have an autoconfigure routine,
the Disk Manager program from Ontrack is excellent. It
probably is the most sophisticated hard disk format tool
available and has many capabilities that make it a desirable
addition to your toolbox.
Disk Manager is a true register-level
format program that goes around the BIOS and manipulates the
disk controller directly. This direct controller access gives
it powerful capabilities that simply are not possible in
programs that work through the BIOS.
Some of these advanced features include
the capability to set head- and cylinder-skew factors. Disk
Manager also can detect intermittent (soft) errors much better
than most other programs can, because it can turn off the
automatic retries that most controllers perform. The program
also can tell when ECC has been used to correct data,
indicating that an error occurred, as well as directly
manipulate the bytes that are used for ECC. Disk Manager has
been written to handle most IDE drives and uses
vendor-specific commands to unlock the capability to perform a
true LLF on IDE drives.
All these capabilities make Disk
Manager one of the most powerful and capable LLF programs
available. Ontrack also offers an excellent package of hard
disk diagnostic and data-recovery utilities called DOS
Utils. Anybody who has to support, maintain, troubleshoot,
repair, or upgrade PCs needs a powerful disk formatter such as
Disk Manager.
HDtest
HDtest is an excellent BIOS-level
format program that will function on virtually any drive that
has an INT 13h ROM BIOS interface, which includes most drives.
HDtest does not have some of the capabilities of true
register-level format programs, but it can be used when the
additional capabilities of a register-level program are not
required. For example, you can use this program to do a quick
wipe of all the data on a drive, no matter what the interface
or controller type is. HDtest also is good for BIOS-level read
and write testing, and has proved to be especially useful in
verifying the functions of disk interface BIOS
code.
HDtest, by Jim Bracking, is a
user-supported software program. This program is distributed
through electronic bulletin boards and public-domain software
libraries. You also can obtain the program from the Public
Software Library, listed in Appendix A. It costs $35, but you
can try it for free.
HDtest has an easy-to-use interface and
pull-down menu system. The program offers all functions that
normally are associated with a standard LLF program, as well
as some extras:
- Normal formatting
- Defect mapping
- Surface analysis
- Interleave test
- Nondestructive low-level
reformat
- Hard disk tests (duplicate of the
IBM Advanced Diagnostics hard disk tests), including tests
for drive seek, head selection, and error detection and
correction, as well as a read/write/verify of the
diagnostics cylinder. This program also can run low-level
ROM BIOS commands to the controller.
HDtest includes most of what you would
want in a generic LLF program and hard disk diagnostics
utility. Its real limitation is that it works only through the
BIOS and cannot perform functions that a true register-level
format program can. In some cases, the program cannot format a
drive that a register-level program could format. Only
register-level programs can perform defect mapping in most IDE
and SCSI environments.
SCSI Low-Level Format
Software
If you are using a SCSI drive, you must
use the LLF program provided by the manufacturer of the SCSI
host adapter. The design of these devices varies enough that a
register-level program can work only if it is tailored to the
individual controller. Fortunately, all SCSI host adapters
include such format software, either in the host adapter's
BIOS or in a separate disk-based program.
The interface to the SCSI drive is
through the host adapter. SCSI is a standard, but there are no
true standards for what a host adapter is supposed to look
like. This means that any formatting or configuration software
will be specific to a particular host adapter. For example,
IBM supplies formatting and defect-management software that
works with the IBM PS/2 SCSI host adapters directly on the
PS/2 Reference disk. That software performs everything that
needs to be done to a SCSI hard disk connected to an IBM host
adapter. IBM has defined a standard interface to its adapter
through an INT 13h and INT 4Bh BIOS interface in a ROM
installed on the card. The IBM adapters also include a special
ABIOS (Advanced BIOS) interface that runs in the processor's
protected mode of operation (for use under protected-mode
operating systems such as OS/2).
Other SCSI host adapters often include
the complete setup, configuration, and formatting software in
the host adapter's on-board ROM BIOS. Most of these adapters
also include an INT 13h interface in the BIOS. The best
example is the Adaptec 1540/1542C adapters, which include
software in ROM that completely configures the card and all
attached SCSI devices.
NOTE: Notice that SCSI format and
configuration software is keyed to the host adapter and is
not specific in any way to the particular SCSI hard disk
drive that you are using.
IDE Low-Level Format
Software
IDE drive manufacturers have defined
extensions to the standard WD1002/1003 AT interface, which was
further standardized for IDE drives as the ATA (AT Attachment)
interface. The ATA specification provides for vendor-unique
commands, which are manufacturer proprietary extensions to the
standard. To prevent improper low-level formatting, many of
these IDE drives have special codes that must be sent to the
drive to unlock the format routines. These codes vary among
manufacturers. If possible, you should obtain LLF and
defect-management software from the drive manufacturer; this
software usually is specific to that manufacturer's
products.
The custom nature of the ATA interface
drives is the source of some myths about IDE. Many people say,
for example, that you cannot perform an LLF on an IDE drive,
and that if you do, you will wreck the drive. This statement
is untrue! What can happen is that in some drives, you may be
able to set new head and sector skew factors that are not as
optimal for the drive as the ones that the manufacturer set,
and you also may be able to overwrite the defect-map
information. This situation is not good, but you still can use
the drive with no problems provided that you perform a proper
surface analysis.
Most ATA IDE drives are protected from
any alteration to the skew factors or defect map erasure
because they are in a translated mode. Zoned Recording drives
always are in translation mode and are fully protected. Most
ATA drives have a custom command set that must be used in the
format process; the standard format commands defined by the
ATA specification usually do not work, especially with
intelligent or Zoned Recording IDE drives. Without the proper
manufacturer-specific format commands, you will not be able to
perform the defect management by the manufacturer-specified
method, in which bad sectors often can be spared.
Currently, the following manufacturers
offer specific LLF and defect-management software for their
own IDE drives:
- Seagate
- Maxtor
- Western Digital
- IBM
These utilities are available for
downloading on the various BBSes run by these companies. The
numbers appear in Appendix A.
Conner Peripherals drives are unique in
that they cannot be low-level formatted through the standard
interface; they must be formatted by a device that attaches to
a special diagnostics and setup port on the drive. You see
this device as a 12-pin connector on Conner drives. A company
called TCE sells an inexpensive device that attaches your PC
to this port through a serial port in your system, and
includes special software that can perform sophisticated test,
formatting, and surface-analysis operations. The product is
called The Conner. (TCE is listed in Appendix A.)
For other drives, I recommend Disk
Manager by Ontrack, as well as the MicroScope program by Micro
2000. These programs can format most IDE drives because they
know the manufacturer-specific IDE format commands and
routines. They also can perform defect-mapping and
surface-analysis procedures.
Nondestructive
Formatters
General-purpose, BIOS-level,
nondestructive formatters such as Calibrate and SpinRite are
not recommended in most situations for which a real LLF is
required. These programs have several limitations and problems
that limit their effectiveness; in some cases, they can even
cause problems with the way defects are handled on a drive.
These programs attempt to perform a track-by-track LLF by
using BIOS functions, while backing up and restoring the track
data as they go. These programs do not actually perform a
complete LLF, because they do not even try to LLF the first
track (Cylinder 0, Head 0) due to problems with some
controller types that store hidden information on the first
track.
These programs also do not perform
defect mapping in the way that standard LLF programs do, and
they can even remove the carefully applied sector header
defect marks during a proper LLF. This situation potentially
allows data to be stored in sectors that originally were
marked defective and may actually void the manufacturer's
warranty on some drives. Another problem is that these
programs work only on drives that are already formatted and
can format only drives that are formattable through BIOS
functions.
A true LLF program bypasses the system
BIOS and send commands directly to the disk controller
hardware. For this reason, many LLF programs are specific to
the disk controller hardware for which they are designed. It
is virtually impossible to have a single format program that
will run on all different types of controllers. Many hard
drives have been incorrectly diagnosed as being defective
because the wrong format program was used and the program did
not operate properly.
Drive Partitioning
Partitioning a hard disk is the
act of defining areas of the disk for an operating system to
use as a volume. To DOS, a volume is an area of a disk denoted
as a drive letter; for example, drive C is volume C, drive D
is volume D, and so on. Some people think that you have to
partition a disk only if you are going to divide it into more
than one volume. This is a misunderstanding; a disk must be
partitioned even if it will be the single volume C.
When a disk is partitioned, a master
partition boot sector is written at cylinder 0, head 0, sector
1--the first sector on the hard disk. This sector contains
data that describes the partitions by their starting and
ending cylinder, head, and sector locations. The partition
table also indicates to the ROM BIOS which of the partitions
is bootable and, therefore, where to look for an operating
system to load. A single hard disk can have 1 to 24
partitions. This number includes all the hard drives installed
in the system, which means that you can have as many as 24
separate hard disks with one partition each, a single hard
disk with 24 partitions, or a combination of disks and
partitions such that the total number of partitions is no more
than 24. If you have more than 24 drives or partitions, DOS
does not recognize them, although other operating systems may.
What limits DOS is that a letter is used to name a volume, and
the Roman alphabet ends with Z--the 24th volume, when you
begin with C.
FDISK
The DOS FDISK program is the accepted
standard for partitioning hard disks. Partitioning prepares
the boot sector of the disk in such a way that the DOS FORMAT
program can operate correctly; it also enables different
operating systems to coexist on a single hard disk.
If a disk is set up with two or more
partitions, FDISK shows only two total DOS partitions: the
primary partition and the extended partition. The extended
partition then is divided into logical DOS volumes, which are
partitions themselves. FDISK gives a false impression of how
the partitioning is done. FDISK reports that a disk divided as
C, D, E, and F is set up as two partitions, with a primary
partition having a volume designator of C and a single
extended partition containing logical DOS volumes D, E, and F.
But in the real structure of the disk, each logical DOS volume
is a separate partition with an extended partition boot sector
describing it. Each drive volume constitutes a separate
partition on the disk, and the partitions point to one another
in a daisy-chain arrangement.
The minimum size for a partition in any
version of DOS is one cylinder; however, FDISK in DOS 4 and
later versions allocates partitions in megabytes, meaning that
the minimum-size partition is 1M. DOS 4.x and later versions
permit individual partitions or volumes to be as large as 2G,
whereas versions of DOS earlier than 4.0 have a maximum
partition size of 32M.
The current DOS (version 7 underlying
Windows 95 OSR2) supports partition sizes of up to 2T using
FAT 32.
FDISK Undocumented
Functions
FDISK is a very powerful program, and
in DOS 5 and later versions, it gained some additional
capabilities. Unfortunately, these capabilities were never
documented in the DOS manual and remain undocumented even in
DOS 7. The most important undocumented parameter in FDISK is
the /MBR (Master Boot Record) parameter, which causes
FDISK to rewrite the Master Boot Sector code area,
leaving the partition tables intact.
CAUTION: Beware: It will
overwrite the partition tables if the two signature bytes at
the end of the sector (55AAh) are damaged. This situation is
highly unlikely, however. In fact, if these signature bytes
were damaged, you would know; the system would not boot and
would act as though there were no partitions at all.
The /MBR parameter seems to be
tailor-made for eliminating boot-sector virus programs that
infect the Master Partition Boot Sector (Cylinder 0, Head 0,
Sector 1) of a hard disk. To use this feature, you simply
enter FDISK /MBR
FDISK then rewrites the boot sector
code, leaving the partition tables intact. This should not
cause any problems on a normally functioning system, but just
in case, I recommend backing up the partition table
information to floppy disk before trying it. You can do this
with the following command: MIRROR /PARTN
This procedure uses the MIRROR
command to store partition-table information in a file called
PARTNSAV.FIL, which should be stored on a floppy disk for
safekeeping. To restore the complete partition-table
information, including all the master and extended partition
boot sectors, you would use the UNFORMAT command as
follows: UNFORMAT /PARTN
This procedure causes the
UNFORMAT command to ask for the floppy disk
containing the PARTNSAV.FIL file and then to restore that file
to the hard disk.
Note that if you are using Windows 95,
the MIRROR and UNFORMAT programs have been
eliminated, and you will have to purchase Norton Utilities
instead.
FDISK also has three other undocumented
parameters: /PRI:, /EXT:, and
/LOG:. These parameters can be used to have FDISK
create master and extended partitions, as well as logical DOS
volumes in the extended partition, directly from the command
line rather than through the FDISK menus. This feature was
designed so that you can run FDISK in a batch file to
partition drives automatically. Some system vendors probably
use these parameters (if they know about them, that is!) when
setting up systems on the production line. Other than that,
these parameters have little use for a normal user, and in
fact may be dangerous!
Other Partitioning
Software
Since DOS 4, there has been little need
for aftermarket disk partitioning utilities, except in special
cases. If a system is having problems that cause you to
consider using a partitioning utility, I recommend that you
upgrade to a newer version of DOS instead. Using nonstandard
partitioning programs to partition your disk jeopardizes the
data in the partitions and makes recovery of data lost in
these partitions extremely difficult.
The reason why disk partitioning
utilities other than FDISK even existed is that the maximum
partition size in older DOS versions was restricted: 16M for
DOS 2.x and 32M for DOS 3.x. These limits are bothersome for
people whose hard disks are much larger than 32M, because they
must divide the hard disk into many partitions to use all of
the disk. Versions of DOS before 3.3 cannot even create more
than a single DOS-accessible partition on a hard disk. If you
have a 120M hard disk and are using DOS 3.2 or an earlier
version, you can access only 32M of that disk as a C
partition.
To overcome this limitation, several
software companies created enhanced partitioning programs
which you can use rather than FDISK. These programs create
multiple partitions and partitions larger than 32M on a disk
that DOS can recognize. These partitioning programs include a
high-level format program, because the FORMAT program in DOS
3.3 and earlier versions can format partitions only up to
32M.
Disk Manager by Ontrack is probably the
best-known of the partitioning utilities. These programs
include LLF capabilities, so you can use one of them as a
single tool to set up a hard disk. The programs even include
disk driver software that provides the capability to override
the physical type selections in the system ROM BIOS, enabling
a system to use all of a disk, even though the drive-type
table in the system ROM BIOS does not have an entry that
matches the hard disk.
Many drive vendors and integrators gave
away these nonstandard partitioning and formatting programs,
which makes some purchasers of such products feel that they
must use those drivers to operate the drive. In most cases,
however, better alternatives are available; nonstandard disk
partitioning and formatting can cause more problems than it
solves.
For example, Seagate shipped Ontrack
Disk Manager with its drives larger than 32M. One purpose of
the program is to perform low-level formatting of the drive,
which Disk Manager does well, and I recommend it highly for
this function. If possible, however, you should avoid the
partitioning and high-level formatting functions and stick
with FDISK and FORMAT.
When you use a program other than
standard FDISK and FORMAT to partition and high-level (DOS)
format a drive, the drive is set up in a nonstandard way,
different from pure DOS. This difference can cause trouble
with utilities--including disk cache programs, disk test and
interleave check programs, and data recovery or retrieval
programs--written to function with a standard DOS disk
structure. In many situations that a standard format would
avoid, a nonstandard disk format can cause data loss and also
can make data recovery impossible.
CAUTION: You should use only
standard DOS FDISK and FORMAT to partition or high-level
format your hard disks. If you use aftermarket partitioning
software to create a nonstandard disk system, some programs
that bypass DOS for disk access will not understand the disk
properly and may write in the wrong place. Windows is an
example of a program that bypasses DOS when you turn on the
Use 32-bit Disk Access option in the Control Panel.
It is especially dangerous to use these
partitioning programs to override your ROM BIOS disk-table
settings. Consider the following disaster scenario.
Suppose that you have a Seagate ST-4096
hard disk, which has 1,024 cylinders and nine heads, and
requires that your controller never perform a data-write
modification called write precompensation to cylinders of the
disk. Some drives require this precom-pensation on the inner
cylinders to compensate for the peak shifting that takes place
because of the higher density of data on the (smaller) inner
cylinders. The ST-4096 internally compensates for this effect
and therefore needs no precompensation from the
controller.
Now suppose that you install this drive
in an IBM AT that does not have a ROM BIOS drive table that
matches the drive. The best matching type you can select is
type 18, which enables you to use only 977 cylinders and seven
heads--56.77M of what should be a 76.5M hard disk. If your IBM
AT is one of the older ones with a ROM BIOS dated 01/10/84,
the situation is worse, because its drive-table ends with type
14. In that case, you would have to select type 12 as the best
match, giving you access to 855 cylinders and seven heads, or
only 49.68M of a 76.5M drive.
ROM BIOS drive tables are listed in
Appendix A. Most IBM-compatibles have a more complete
drive-type table and would have an exact table match for this
drive, allowing you to use the full 76.5M with no problems. In
most compatibles with a Phoenix ROM BIOS, for example, you
would select type 35, which would support the drive
entirely.
Now suppose that you are not content
with using only 50M or 57M of this 76.5M drive. You invoke the
SuperPartition aftermarket partitioning program that came with
the drive and use it to LLF the drive. Then you use the
aftermarket program to override the type 18 or type 12
settings in the drive table. The program instructs you to set
up a very small C partition (of only 1M) and then partitions
the remaining 75.5M of the disk as D. This partitioning
overrides the DOS 3.3 32M partition limitation. (If you had an
IBM-compatible system that did not require the drive-type
override, you still would need to use the aftermarket
partitioner to create partitions larger than the DOS 3.3
standard 32M.) Following that, you use the partitioner to
high-level format the C and D partitions, because the DOS
high-level format in DOS 3.3 works only on volumes of 32M or
less.
Most aftermarket partitioners create a
special driver file that they install in the CONFIG. SYS file
through the DEVICE command. After the system boots
from the C partition and loads the device driver, the 75.5M D
partition is completely accessible.
Along comes an innocent user of the
system who always boots from her own DOS floppy disk. After
booting from the floppy, she tries to log into the D
partition. No matter what version of DOS this user boots from
on the floppy disk, the D partition seems to have vanished. An
attempt to log into that partition results in an Invalid
drive specification error message. No standard version of
DOS can recognize that specially created D partition if the
device driver is not loaded.
An attempt by this user to recover data
on this drive with a utility program such as Norton or PC
Tools results in failure, because these programs interpret the
drive as having 977 cylinders and seven heads (type 18) or 855
cylinders and seven heads (type 12). In fact, when these
programs attempt to correct what seems to be partition-table
damage, data will be corrupted in the vanished D
partition.
Thinking that there may be a physical
problem with the disk, the innocent user boots and runs the
Advanced Diagnostics software to test the hard disk. Because
Advanced Diagnostics incorporates its own special boot code
and does not use standard DOS, it does not examine
partitioning but goes to the ROM BIOS drive-type table to
determine the capacity of the hard disk. It sees the unit as
having only 977 or 855 cylinders (indicated by the type 18 or
12 settings), as well as only seven heads. The user then runs
the Advanced Diagnostics hard disk tests, which use the last
cylinder of the disk as a test cylinder for diagnostic read
and write tests. This cylinder subsequently is overwritten by
the diagnostics tests, which the drive passes because there is
no physical problem with the drive.
This innocent user has just wiped out
the D-drive data that happened to be on cylinder 976 in the
type-18 setup or on cylinder 854 in the type-12 setup. Had the
drive been partitioned by FDISK, the last cylinder indicated
by the ROM BIOS drive table would have been left out of any
partitions, being reserved so that diagnostics tests could be
performed on the drive without damaging data.
Beyond the kind of disaster scenario
just described, other potential problems can be caused by
nonstandard disk partitioning and formatting, such as the
following:
- Problems in using the 32-bit Disk
Access feature provided by Windows, which bypasses the BIOS
for faster disk access in 386 Enhanced Mode.
- Data loss by using OS/2, UNIX,
XENIX, Novell Advanced NetWare, or other non-DOS operating
systems that do not recognize the disk or the nonstandard
partitions.
- Difficulty in upgrading a system
from one DOS version to another.
- Difficulty in installing a different
operating system, such as OS/2, on the hard
disk.
- Data loss by using an LLF utility to
run an interleave test; the test area for the interleave
test is the diagnostics cylinder, which contains data on
disks formatted with Disk Manager.
- Data loss by accidentally deleting
or overwriting the driver file and causing the D partition
to disappear after the next boot.
- Data-recovery difficulty or failure
because nonstandard partitions do not follow the rules and
guidelines set by Microsoft and IBM, and no documentation on
their structure exists. The sizes and locations of the FATs
and root directory are not standard, and the detailed
reference charts in this book (which are valid for an
FDISK-created partition) are inaccurate for nonstandard
partitions.
I could continue, but I think you get
the idea. If these utility programs are used only for
low-level formatting, they do not cause problems; it is the
drive-type override, partitioning, and high-level format
operations that cause difficulty. If you consider data
integrity to be important, and you want to be able to perform
data recovery, follow these disk support and partitioning
rules:
- Every hard disk must be properly
supported by system ROM BIOS, with no software overrides. If
the system does not have a drive table that supports the
full capacity of the drive, accept the table's limit,
upgrade to a new ROM BIOS (preferably with a user-definable
drive-type setting), or use a disk controller with an
on-board ROM BIOS for drive support.
- Use only FDISK to partition a hard
disk. If you want partitions larger than 32M, use DOS 4 or a
later version.
High-Level (Operating-System)
Format
The final step in the software
preparation of a hard disk is the DOS high-level format. The
primary function of the high-level format is to create a FAT
and a directory system on the disk so that DOS can manage
files. Usually, you perform the high-level format with the
standard DOS FORMAT program, using the following
syntax: FORMAT C: /S /V
This step high-level formats drive C
(or volume C, in a multivolume drive), places the hidden
operating-system files in the first part of this partition,
and prompts for the entry of a volume label to be stored on
the disk at completion.
The high-level format program performs
the following functions and procedures:
- 1. Scans the disk (read only)
for tracks and sectors marked as bad during the LLF, and
notes these tracks as being unreadable.
2. Returns the drive heads to
the first cylinder of the partition, and at that cylinder,
head 1, sector 1, writes a DOS volume boot
sector.
3. Writes a FAT at head 1,
sector 2. Immediately after this FAT, it writes a second
copy of the FAT. These FATs essentially are blank except for
bad-cluster marks noting areas of the disk that were found
to be unreadable during the marked-defect scan.
4. Writes a blank root
directory.
5. If the /S
parameter is specified, copies the system files (IBMBIO.COM
and IBMDOS.COM or IO.SYS and MSDOS.SYS, depending on which
DOS you run) and COMMAND.COM files to the disk (in that
order).
6. If the /V
parameter is specified, prompts the user for a volume label,
which is written as the fourth file entry in the root
directory.
Now DOS can use the disk for storing
and retrieving files, and the disk is a bootable disk.
NOTE: The Format command
can be run through the Windows Explorer within Windows 95
even on hard disks, as long as no files are open. You cannot
format the drive where Windows 95 resides.
During the first phase of the
high-level format, a marked defect scan is performed. Defects
marked by the LLF operation show up during this scan as being
unreadable tracks or sectors. When the high-level format
encounters one of these areas, it automatically performs up to
five retries to read these tracks or sectors. If the
unreadable area was marked by the LLF, the read fails on all
attempts.
After five retries, the DOS FORMAT
program gives up on this track or sector and moves to the
next. Areas that remain unreadable after the initial read and
the five retries are noted in the FAT as being bad clusters.
DOS 3.3 and earlier versions can mark only entire tracks bad
in the FAT, even if only one sector was marked in the LLF. DOS
4 and later versions individually check each cluster on the
track and recover clusters that do not involve the LLF
marked-bad sectors. Because most LLF programs mark all the
sectors on a track as bad, rather than the individual sector
that contains the defect, the result of using DOS 3.3 or 4 is
the same: all clusters involving sectors on that track are
marked in the FAT as bad.
NOTE: Some LLF programs mark only
the individual sector that is bad on a track, rather than
the entire track. This is true of the IBM PS/2 low-level
formatters on the IBM PS/2 Advanced Diagnostics or Reference
disk. In this case, high-level formatting with DOS 4 or
later versions results in fewer lost bytes in bad sectors,
because only the clusters that contain the marked bad
sectors are marked bad in the FAT. DOS 4 and later versions
display the Attempting to recover allocation unit x message
(in which x is the number of the cluster) in an attempt to
determine whether a single cluster or all the clusters on
the track should be marked bad in the FAT.
If the controller and LLF program
together support sector and track sparing, the high-level
format finds the entire disk defect-free, because all the
defective sectors have been exchanged for spare good
ones.
If a disk has been low-level formatted
correctly, the number of bytes in bad sectors is the same
before and after the high-level format. If the number does
change after you repeat a high-level format (reporting fewer
bytes or none), the LLF was not done correctly. The
manufacturer's defects were not marked correctly; or Norton,
Mace, PC Tools, or a similar utility was used to mark
defective clusters on the disk. The utilities cannot mark the
sectors or tracks at the LLF level; the bad-cluster marks that
they make are stored only in the FAT and erased during the
next high-level format operation. Defect marks made in the LLF
consistently show up as bad bytes in the high-level format, no
matter how many times you run the format.
Only an LLF or a surface-analysis tool
can correctly mark defects on a disk; anything else makes only
temporary bad-cluster marks in the FAT. This kind of marking
may be acceptable temporarily, but when additional bad areas
are found on a disk, you should run a new LLF of the disk and
either mark the area manually or run a surface analysis to
place a more permanent mark on the disk.
Hard Disk Drive
Troubleshooting and Repair
If a hard disk drive has a problem
inside its sealed HDA, repairing the drive usually is not
feasible. If the failure is in the logic board, you can
replace that assembly with a new or rebuilt assembly easily
and at a much lower cost than replacing the entire
drive.
Most hard disk problems really are not
hardware problems; instead, they are soft problems that can be
solved by a new LLF and defect-mapping session. Soft
problems are characterized by a drive that sounds normal
but produces various read and write errors.
Hard problems are mechanical,
such as when the drive sounds as though it contains loose
marbles. Constant scraping and grinding noises from the drive,
with no reading or writing capability, also qualify as hard
errors. In these cases, it is unlikely that an LLF will put
the drive back into service. If a hardware problem is
indicated, first replace the logic-board assembly. You can
make this repair yourself and, if successful, you can recover
the data from the drive.
If replacing the logic assembly does
not solve the problem, contact the manufacturer or a
specialized repair shop that has clean-room facilities for
hard disk repair. (See Appendix B for a list of drive
manufacturers and companies that specialize in hard disk drive
repair.)
17xx, 104xx, and
210xxxx Hardware Error Codes
When a failure occurs in the hard disk
subsystem at power-on, the Power-On Self Test (POST)
finds the problem and reports it with an error message. The
17xx, 104xx, and
210xxxx errors during the POST or while
running the Advanced Diagnostics indicate problems with hard
disks, controllers, or cables. The 17xx codes
apply to ST-506/412 interface drives and controllers;
104xx errors apply to ESDI drives and
controllers; and 210xxxx errors apply to SCSI
drives and host adapters.
Table 16.11 shows a breakdown of these
error messages and their meanings.
Table 16.11 Hard Disk and
Controller Diagnostic Error Codes
ST-506/412 Drive and Controller
Error Codes
Error |
Description |
1701 |
Fixed disk general POST error |
1702 |
Drive/controller time-out error |
1703 |
Drive seek error |
1704 |
Controller failed |
1705 |
Drive sector not found error |
1706 |
Write fault error |
1707 |
Drive track 0 error |
1708 |
Head select error |
1709 |
Error Correction Code (ECC) error |
1710 |
Sector buffer overrun |
1711 |
Bad address mark |
1712 |
Internal controller diagnostics
failure |
1713 |
Data compare error |
1714 |
Drive not ready |
1715 |
Track 0 indicator failure |
1716 |
Diagnostics cylinder errors |
1717 |
Surface read errors |
1718 |
Hard drive type error |
1720 |
Bad diagnostics cylinder |
1726 |
Data compare error |
1730 |
Controller error |
1731 |
Controller error |
1732 |
Controller error |
1733 |
BIOS undefined error return |
1735 |
Bad command error |
1736 |
Data corrected error |
1737 |
Bad track error |
1738 |
Bad sector error |
1739 |
Bad initialization error |
1740 |
Bad sense error |
1750 |
Drive verify failure |
1751 |
Drive read failure |
1752 |
Drive write failure |
1753 |
Drive random read test failure |
1754 |
Drive seek test failure |
1755 |
Controller failure |
1756 |
Controller Error Correction Code (ECC)
test failure |
1757 |
Controller head select failure |
1780 |
Seek failure; drive 0 |
1781 |
Seek failure; drive 1 |
1782 |
Controller test failure |
1790 |
Diagnostic cylinder read error; drive
0 |
1791 |
Diagnostic cylinder read error; drive
1 |
SCSI Drive and Host Adapter Error
Codes |
|
096xxxx |
SCSI adapter with cache (32-bit)
errors |
112xxxx |
SCSI adapter (16-bit without cache)
errors |
113xxxx |
System board SCSI adapter (16-bit)
errors |
210xxxx |
SCSI fixed disk
errors |
The first x in xxxx is
the SCSI ID number. The second x in xxxx is
the logical unit number (usually 0). The third x in
xxxx is the host adapter slot number. The fourth x
in xxxx is a letter code indicating drive
capacity.
Most of the time, a seek failure
indicates that the drive is not responding to the controller.
This failure usually is caused by one of the following
problems:
- Incorrect drive-select jumper
setting
- Loose, damaged, or backward control
cable
- Loose or bad power
cable
- Stiction between drive heads and
platters
- Bad power supply
If a diagnostics cylinder read error
occurs, the most likely problems are these:
- Incorrect drive-type
setting
- Loose, damaged, or backward data
cable
- Temperature-induced mistracking
The methods for correcting most of
these problems are obvious. If the drive-select jumper setting
is incorrect, for example, correct it. If a cable is loose,
tighten it. If the power supply is bad, replace it. You get
the idea.
If the problem is temperature-related,
the drive usually will read data acceptably at the same
temperature at which it was written. Let the drive warm up for
a while and then attempt to reboot it, or let the drive cool
and reread the disk if the drive has overheated.
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