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:


Ive 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


mount -v $LVTYPE -o log=/dev/$LOGDEV,nomanager /dev/$LV $MROOT$FS || $ERROR


If I compare this against my AIX 5.3 system, I dont find any reference to this enhancement.

AIX 7.1:

[/usr/lpp/bosinst] > oslevel -s


[/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


[/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.