Backup and Restore of AIX LVM Performance Tunable Parameters

By Lakshmi Yadlapati posted Fri October 16, 2020 10:33 AM

The lvmo command is used to manage tunables such as the number of LVM pbufs on a per volume group basis. These tunables are stored outside of the on disk volume group in ODM, and are not preserved when the volume group is moved to a new LPAR. The exportvg and importvg of the volume group will set the LVM performance tunables to the default values.

A solution to to migrate tunables with a volume group is to backup lvmo tunables before exporting the VG and to restore the tunables after importing the VG.  A sample script called “lvmo_tool” is provided to demonstrate this.

# lvmo_tool -?                 
getopt: Not a recognized flag: ?
Usage: lvmo_tool -b <vgname>
       lvmo_tool -r <file_name> <vgname>
To back up lvmo tunables:
# lvmo_tool -b testvg                                               
   lvmo tunables are saved in /tmp/lvmo00f6f42a00004c000000015b827ff33f.
   Run “lvmo_tool -r /tmp/lvmo00f6f42a00004c000000015b827ff33f testvg” to restore
         lvmo tunables after importing the VG.
To restore lvmo tunables:
Import the VG with no varyon option
# importvg -y testvg -n hdisk1
restore lvm tunables
# lvmo_tool -r /tmp/lvmo00f6f42a00004c000000015b827ff33f testvg
varyon the VG
# varyonvg testvg
Note:  Restoring lvm tunables on already varied VG requires a varyoff and varyon the VG if
- New values of the tunables are less than the VG’s current values
- Changing max_vg_pbufs of the VG
1 comment



Fri October 16, 2020 11:41 AM

lvmo_tool is integrated in exportvg and importvg commands in In AIX 7.2 TL03.

exportvg [-b] - Backs up the performance tunable parameters of the volume group that are set with the lvmo command.
importvg [ -r file_name ] - Restores the performance tunable parameters of the volume group.