Each administrator, maintaining a
network, should have a standard backup procedure, which should be
implemented nightly. Backup procedures should include tape drives,
tape automation, and full, incremental, and differential back ups.
DAT and DLT are the two standard types
of tape drives. Digital Audio Tape (DAT) provides a complete digital
recording method, which was originally used to record audio and video.
DAT has a capacity of 24 gigabytes, uses a SCSI connection, and is mostly used for medium sized networks.
Digital Linear Tapes (DLT) have a
capacity of up to 80 gigabytes and is becoming the more popular method
of the three backup standards. Although this method is expensive, it
is very fast and reliable. Like DAT, DLT uses a SCSI connection as
well.
Tape automation is a scheduled routine backup, where a tape backup is scheduled
with an average of 20-25 tape rotations. The most common tape backup procedure is the 21-day tape
rotation, where rotation is consistent for four days out of the week,
Monday through Thursday. There are some rotations scheduled for five
days a week as well, Monday through Friday. Storing backup tape
offsite is also a good idea in case of a major catastrophe, which will
ruin the backed up information.
There are three different types of
backups: Full, incremental, and differential. Full back up is the
process where all the information is backed up. Most companies perform
full backups everyday; however, this process requires the most tape
out of the three backup processes.
Incremental backups back up files,
which have been changed since the last incremental or full backup was
performed. This process is less time consuming and uses the least
amount of tape. In case the database needs to be restored, the last
full backup and every incremental tape afterwards would be needed.
Differential backup is a process in
which those files are backed up which were changed since that last
full backup was performed. This type of backup process takes the less
tape than a full backup and when restoring the information, only two
tapes are required; the last full and differential backup tapes.
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