Cluster quorum with quorum nodes and tiebreaker disks
To use cluster quorum with quorum nodes and tiebreaker disks, additional requirements apply.
If a cluster is configured with quorum nodes and tiebreaker disks, it can operate with as few as one available quorum node, if the quorum node has access to a majority of the tiebreaker disks. Setting up this configuration includes the following general steps:
- Designate one or more nodes as quorum nodes.
- 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 example, to add tiebreaker disks to a cluster that is configured only with quorum nodes (without tiebreaker disks) issue the following command:
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, the GPFS daemon must be up and running.
- If the tiebreaker disks are not part of a file system, the GPFS daemon can be 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 a 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: