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While attending the IBM Power Systems Symposium this week, I learnt that starting with AIX 7.1 (and AIX 6.1 TL6) JFS2 logging is disabled during a mksysb restore. You may be familiar with disabling JFS2 logs, if not, take a look at this IBM technical note:
https://www-304.ibm.com/support/docview.wss?uid=isg3T1012643
I’ve been unable to find any official documentation from IBM that mentions this new enhancement to the mksysb restore process. However, when I checked my own AIX 7.1 system I found the following statement/code in the /usr/lpp/bosinst/bi_main script:
# Disable jfs2 logs for temp mounts -- (def#751604 performance)
if [[ "$2" = "TRUE" ]]; then
mount -v $LVTYPE -o log=NULL,nomanager /dev/$LV $MROOT$FS || $ERROR
else
mount -v $LVTYPE -o log=/dev/$LOGDEV,nomanager /dev/$LV $MROOT$FS || $ERROR
fi
If I compare this against my AIX 5.3 system, I don’t find any reference to this enhancement.
AIX 7.1:
[/usr/lpp/bosinst] > oslevel -s
7100-00-03-1115
[/usr/lpp/bosinst] # grep log=NULL bi_main
bi_main: mount -v $LVTYPE -o log=NULL,nomanager /dev/$LV $MROOT$FS || $ERROR
AIX 5.3:
[/usr/lpp/bosinst] > oslevel -s
5300-11-03-1013
[/usr/lpp/bosinst] # grep log=NULL bi_main
[/usr/lpp/bosinst] #
This change is clever. I mean why would we ever need JFS2 logging during a restore? By disabling logging, the restore process will be faster. Simple, really.
