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