Data Consistency, Recovery, and Migration 4-45

Data Restore: When Should You Do It?

Data Restore: When Should You Do It?
Threetypes of situations could occur in an OnLine environment that would
require you, as OnLine administrator, to perform a data restore:
■You want to replace one or more disks.
■Your disk experiences a media failure.
■Your OnLine data experiences extreme corruption.
A data restore re-creates the OnLine system that was in effect at the time of
your most-recent archive, plus any changes that have been backed up to a
logical log tape.
You cannot restore a selected table or database. Since you perform a data
restorefrom the complete set of archive and logical log backup tapes, OnLine
restores the complete contents of those tapes, which include all OnLine
databases.Refer to page 4-45 for a description ofwhat happens during a data
restore.
Outlinedbelow are the main steps that are part of the data restore procedure.
Following this list, each item is described in greater detail. If you press the
Interrupt key at any time during the restore, you must repeat the entire
procedure.

Steps That Occur During a Data Restore

1. Gather all archive and logical log backup tapes needed for the
restore.
2. Verify that your current shared-memory parameters are set to the
maximum value assigned since the last archive (any level).
3. Verify that your current device (and mirroring) configuration
matches the configuration that was in effect at the time of the last
archive (any level).
4. Verifythat all raw devices that have been in use since the last archive
are available.
5. Take OnLine to offline mode.
6. Select the DB-Monitor Archive menu, Restore option or execute
tbtape -r.