Cluster quorum with quorum nodes and tiebreaker disks

To use cluster quorum with quorum nodes and tiebreaker disks, more requirements apply.

If a cluster is configured with quorum nodes and tiebreaker disks, then it can operate with as few as one available quorum node. This condition is applicable only when the quorum node has access to most of the tiebreaker disks. Setting up this configuration includes the following general steps:
  1. Designate one or more nodes as quorum nodes.
  2. Define one to three disks as tiebreaker disks, by issuing the mmchconfig command with the tiebreakerDisks parameter. You can designate any disk to be a tiebreaker disk.
For more information, see Quorum.
For example, to add tiebreaker disks to a cluster that is configured only with quorum nodes (without tiebreaker disks) issue the following command: 
mmchconfig tiebreakerDisks="nsdName[;nsdName...]"
where nsdName is the name of a disk.
The following requirements must be met:
  • If a GPFS cluster includes more than eight quorum nodes, the cluster configuration cannot be changed to cluster quorum with quorum nodes and tiebreaker disks.
  • The cluster can have up to three tiebreaker disks.
  • The tiebreaker disks must be directly attached to all the quorum nodes.
  • When you add tiebreaker disks, you might have to shut down the GPFS daemon:
    • If the tiebreaker disks are part of a file system, then the GPFS daemon must be up and running.
    • If the tiebreaker disks are not part of a file system, then the GPFS daemon is either running or shut down.
  • If a cluster uses the traditional server-based (non-CCR) configuration repository, you must shut down the GPFS daemons on all the nodes in the cluster before you issue the mmchconfig tiebreakerDisks command.
To revert from cluster quorum with quorum nodes and tiebreaker disks to cluster quorum with quorum nodes only, issue the following command:
mmchconfig tiebreakerDisks=DEFAULT