In databases with extremely high transaction log volume
workloads,
and which are configured for HADR with one or more AUXILIARY
Standby databases, the HADR_LOG_GAP between the Primary database
and the Auxiliary Standby database(s) may increase significantly
during the INCLUDE LOGS phase of the Online Backup. The
HADR_LOG_GAP will recover to normal upon completion of the
Online Backup. |
Upgrading to the Fix Pack inclusive of this APAR fix may provide
relief.
Also, utilizing the online Backup EXCLUDE LOGS option will
resolve the symptom.
When the online Backup EXCLUDE LOGS option is used, users will
need to self manage and save the log files required to restore
this online backup image at a later date. The following
instructions may help you assess if this is a viable alternative
in your environment:
1. Perform the online Backup using the EXCLUDE LOGS option.
2. Upon completion of the online backup, you can determine the
span of logs that would need to be saved in order to restore
this backup image to a consistent point in time, by querying the
DB_HISTORY administrative view:
(Note in my query below, I return only the most recent backup
operation by filtering OPERATION= 'B' and ordering by START_TIME
descending and using the FETCH FIRST 1 ROWS clause).
$ db2 select "OPERATION, substr(BACKUP_ID,1,20) as BACKUP_ID,
START_TIME, substr(FIRSTLOG,1,20) as FIRSTLOG,
substr(LASTLOG,1,20) as LASTLOG from SYSIBMADM.DB_HISTORY where
OPERATION='B' order by START_TIME desc fetch first 1 rows only"
OPERATION BACKUP_ID START_TIME FIRSTLOG
LASTLOG
--------- -------------------- --------------
-------------------- --------------------
B - 20180221153249 S0000106.LOG
S0000108.LOG
1 record(s) selected.
3. Copy this span of log files for safe keeping wherever the
backup image is stored.
Note, if you retain archived log files for a period of time that
aligns with the oldest possible restore you may need, then you
may not actually need to save the log files with the backup
images, since you will already have them in the the archive log
path.
4. When restoring a backup image at a later date, the path to
these log files can be provided by using the OVERFLOW LOG PATH
option. You can either specify the path of your log
archive location (as I've done below), or the path to wherever
you saved the log files with the backup image files. You can
perform a rollforward to end-of-backup (as I've done below), or
end-of-logs if you prefer.
$ db2 restore db HADR105 taken at 20180221153249
DB20000I The RESTORE DATABASE command completed successfully.
$ db2 "rollforward db hadr105 to end of backup overflow log path
(/home/dsciaraf/mylogarchpath/dsciaraf/HADR105/NODE0000/LOGSTREA
M0000/C0000000/)"
Rollforward Status
Input database alias = hadr105
Number of members have returned status = 1
Member ID = 0
Rollforward status = DB working
Next log file to be read = S0000109.LOG
Log files processed = S0000106.LOG -
S0000108.LOG
Last committed transaction =
2018-02-21-20.33.03.000000 UTC
DB20000I The ROLLFORWARD command completed successfully. |
