How to run two independent Incremental backup Cycles
Last updated on OCTOBER 11, 2016
Applies to:Oracle Database - Enterprise Edition - Version 18.104.22.168 and later
Information in this document applies to any platform.
Sometimes there is a need to run two separate incremental backup cycles.
Often one cycle may be on DISK, the other on tape but not necessarily always.
The type of incremental may also differ : a traditional repeating level 0/level 1 cycle and a second, incremental merge (Oracle Suggested Backup).
An incremental level N backup is based on the checkpoint of the previous incremental at the same or lower level, so when two backup cycles on the same target are run, care must be taken to ensure the two do not interfere with one another.
Consider this example:
Regular incremental backups to tape are done with tag 'TAPE CYCLE'.
A new incremental merge backup cycle to disk is to be introduced after the next TAPE level 0 completes.
The backup script commands for TAPE CYCLE are:
Note 1: The datafilecopies for the incremental merge is created after this backup - datafile copy checkpoint scn for file# 1 is 6995619.
Note 2: The first TAPE CYCLE incremental should have been based in the checkpoint scn of the previous TAPE CYCLE level 0 (6995532).
However, the most recent level 0 is no longer the tape level 0, it is the datafile copy with checkpoint scn 6995619.
Already, this TAPE CYCLE incremental cannot be used to recover the TAPE CYCLE Level 0 backup, as it is based on the datafilecopy.
Note 3: The MERGE cycle backup is using the syntax 'for recover of copy with tag 'MERGE'' so only backups with this tag are considered and the backup is correctly based
on the checkpoint of the datafilecopy
Note 4: The next TAPE CYCLE level 1 is again based on previous level 1 which again, is from the wrong cycle (MERGE)
So the incremental merge backup is working correctly as it is using the 'for recover of copy with tag' syntax to ensure all backups are based on previous backups with the same tag only. However it is interfering with the established TAPE CYCLE incremental backups and will render all the tape incrementals unusable.
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