Nonquorum volume groups

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The Logical Volume Manager (LVM) automatically deactivates the volume group when it lacks a quorum of Volume Group Descriptor Areas (VGDAs) or Volume Group Status Areas (VGSAs). However, you can choose an option that allows the group to stay online as long as there is one VGDA/VGSA pair intact. This option produces a nonquorum volume group.

The LVM requires access to all of the disks in nonquorum volume groups before allowing reactivation. This ensures that the VGDA and VGSA are up-to-date.

You might want to produce a nonquorum volume group in systems where every logical volume has at least two copies. If a disk failure occurs, the volume group remains active as long as there is one active disk.

Note: Both user-defined and rootvg volume groups can operate in nonquorum status, but the methods used to configure user-defined volume groups and rootvg volume groups as nonquorum and for recovery after hardware failures are different. Be sure you use the correct method for the appropriate volume group.

Even when you are using nonquorum volume groups, it is possible to lose quorum and see the following message in the errpt command output:

QUORUM LOST,  VOLUME GROUP CLOSING LVM.

This message occurs when all physical volumes are in the missing state and the LVM automatically varies off the volume group.

The message says QUORUM LOST because disabling quorum on a volume group reduces the quorum requirement to 1. You can use the lsvg vgname command to display the quorum value which is in the QUORUM: field. In the case where all physical volumes are missing, even this minimum quorum requirement is violated, resulting in the lost quorum message and an automatic vary off of the volume group.