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A QUORUM of disks required to | This field is |
keep the volume group online? | page 88 for a discussion of quorum in an HACMP |
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3.4.4.4Varying Off the Volume Group on the Destination Nodes Use the varyoffvg command to deactivate the shared volume group so that it can be imported onto another destination node or activated as appropriate by the cluster event scripts. Enter: varyoffvg volume_group_name.
3.4.5Quorum
Note
This section does not apply to the IBM
Quorum is a feature of the AIX LVM that determines whether or not a volume group can be placed online using the varyonvg command, and whether or not it can remain online after a failure of one or more of the physical volumes in the volume group.
Each physical volume in a volume group has a Volume Group Descriptor Area (VGDA) and a Volume Group Status Area (VGSA).
VGDA Describes the physical volumes (PVs) and logical volumes (LVs) that make up a volume group and maps logical partitions to physical partitions. The varyonvg command reads information from this area.
VGSA Maintains the status of all physical volumes and physical partitions in the volume group. It stores information regarding whether a physical partition is potentially inconsistent (stale) with mirror copies on other physical partitions, or is consistent or synchronized with its mirror copies. Proper functioning of LVM mirroring relies upon the availability and accuracy of the VGSA data.
3.4.5.1 Quorum at Vary On
When a volume group is brought online using the varyonvg command, VGDA and VGSA data structures are examined. If more than half of the copies are readable and identical in content, quorum is achieved and the varyonvg
