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Operating OnLine 3-47
Plan the Archive Schedule
Plan the Archive Schedule
Each of the following considerations affects the archive schedule you create
for your environment:
■ If you want to minimize the time for a restore
■ If you want to minimize the time to create an archive
■ If you want to create online archives
■ If you must use the same tape drive to create archives and to back up
the logical logs
■ If the operator is periodically unavailable
Try to avoid unscheduled archives. Because the following administrative
changes require a level-0 archive as part of the procedure, consider waiting
to make these changes until your next regularly scheduled level-0 archive:
■ Changing a tape device pathname from /dev/null (archive after)
■ Adding logging to a database (archive before)
■ Mirroring a dbspace that contains logical log files (archive after to
initiate mirroring)
■ Adding a logical log file (archive after to make log file available)
■ Dropping a logical log file (archive after)
■ Moving one or more logical log files (archives during the procedure)
■ Changing the size of the physical log (archive after reinitializing
shared memory)
To ensure the integrity of your archives, periodically verify that all OnLine
data and control information is consistent before you create a level-0 archive.
You need not perform this checking before every level-0 archive, but
Informix recommends thatyou keep the necessary tapes from the most recent
archive created immediately after OnLine was verified to be consistent. Refer
to page 4-6 for a detailed explanation of this consistency check.
During a restore, OnLine reads and writes all relevant archive tapes to disk.
Then OnLine reads all logical log files since the last archive and rolls the log
records forward. The time required to perform a restore is a function of two
things: