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Data Backup 12-9
you to load additional tapes. If you start the
dump
command through
rsh
, you
do not see the prompts from the filer and the
dump
command cannot be com-
pleted because of the lack of tapes.
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You must meet these prerequisites before you can determine the number of tape
files required:
The filer must be able to display tape drive information. To learn how to display
tape drive information, refer to Displaying Tape Device Information in
Chapter 14.
You must know the amount of data to be backed up. For information about deter-
mining the amount of backup data, refer to Determining the Amount of Backup
Data.
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Follow these steps to determine the number of tapes required for the backup:
1. Determine the capacity of the tape drives you are using for the backup.
2. Determine the amount of data that needs to be backed up.
3. Determine the amount of space that will be left unused on a tape. For example, if
the
dump
command specifies several tape files, the command automatically
writes to the next tape file even though there is space left in the current tape.
Example: The following
dump
command starts the second tape file on
rst1a
after writing 2,000,000 tape blocks to the first tape file, even though the tape in
rst0a
contains unused space:
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The prerequisites for the
dump
command depend on the format of the
dump
com-
mand. For example, the prerequisites for backing up data to a remote tape drive and
to a local tape drive are different. This section describes the general prerequisites that
must be met regardless of the
dump
command format. It also describes the specific
prerequisites for specific backup procedures.