Where to find recovery information
Information that is needed for recovery is contained in several locations.
- SYSIBM.SYSCOPY
- SYSIBM.SYSCOPY is a catalog table that contains information about
full and incremental image copies. If concurrent updates were allowed
when making the copy, the log RBA corresponds to the image copy start
time; otherwise, it corresponds to the end time. The RECOVER utility
uses the log RBA to look for log information after restoring the image
copy. The SYSCOPY catalog table also contains information that is
recorded by the COPYTOCOPY utility.
SYSCOPY also contains entries with the same kinds of log RBAs that are recorded by the utilities QUIESCE, REORG, LOAD, REBUILD INDEX, RECOVER TOCOPY, and RECOVER TOLOGPOINT.
When the REORG utility is used, the time at which Db2 writes the log RBA to SYSIBM.SYSCOPY depends on the value of the SHRLEVEL parameter:
- For SHRLEVEL NONE, the log RBA is written at the end of the reload
phase.
If a failure occurs before the end of the reload phase, the RBA is not written to SYSCOPY.
If a failure occurs after the reload phase is complete (and therefore, after the log RBA is written to SYSCOPY), the RBA is not backed out of SYSCOPY.
- For SHRLEVEL REFERENCE and SHRLEVEL CHANGE, the log RBA is written
at the end of the switch phase.
If a failure occurs before the end of the switch phase, the RBA is not written to SYSCOPY.
If a failure occurs after the switch phase is complete (and thus, after the log RBA is written to SYSCOPY), the RBA is not backed out of SYSCOPY.
The log RBA is put in SYSCOPY regardless of whether the LOG option is YES or NO, or whether the UNLOAD PAUSE option is specified.
When DSNDB01.DBD01, DSNDB01.SYSUTILX, DSNDB06.SYSTSCPY, and DSNDB01.SYSDBDXA are quiesced or copied, a SYSCOPY record is created for each table space and any associated index that has the COPY YES attribute. For recovery reasons, the SYSCOPY records for these three objects are placed in the log.
- For SHRLEVEL NONE, the log RBA is written at the end of the reload
phase.
- SYSIBM.SYSLGRNX
- SYSIBM.SYSLGRNX is a directory table that contains records of
the log RBA ranges that are used during each period of time that any
recoverable page set is open for update. Those records speed recovery
by limiting the scan of the log for changes that must be applied.
If you discard obsolete image copies, you should consider removing their records from SYSIBM.SYSCOPY and the obsolete log ranges from SYSIBM.SYSLGRNX.
- BSDS (bootstrap data set)
- The BSDS contains information about system-level backups, and
the Db2 archive
log data sets. The RECOVER utility uses the recovery base log point
RBA or LRSN value associated with the system-level backup to look
for the log information after restoring the object from the system-level
backup.
In a data-sharing environment, each Db2 member keeps track of the system-level backups taken on that particular member in its BSDS.
- DFSMShsm
- The RECOVER utility queries DFSMShsm for information about whether a system-level backup resides on disk or tape.