Quorum server

[Jose_C_Moraes]

Hi I need help.

Quorum server is required with how many nodes ( minimum ) ?

TIA and best regards

Jose

[Ken Grabowski]

Not sure there is a minimum. I've used it with only 3 node.

[Matti_Kurkela]

The actual issue is the cluster lock: it can be either a lock disk, a lock LUN or a quorum server.

• A one-node cluster will not use the safety timer mechanism, and therefore won't really need a cluster lock, although with some Serviceguard versions, the configuration tools may insist on it. But if you have only one node, why set up a cluster at all?
• A two-node cluster requires a cluster lock, otherwise both nodes will crash and reboot when the cluster heartbeat fails. This would make the cluster rather useless (it would act as a fault-sensitive rather than a fault-tolerant system).
• A three-node cluster is strongly recommended to have a cluster lock, in case a failure happens when e.g. one of the nodes is down for scheduled maintenance.
• For larger clusters, a cluster lock is recommended but not absolutely required. If you have more than four nodes, you cannot use a lock disk, but you can use a quorum server.

A quorum server can be used in clusters of any size. We have successfully used it with several 2-node clusters. Before Serviceguard version A.11.19 it helped in minimizing service breaks during SAN migrations, as the older Serviceguard versions did not allow reconfiguring the cluster lock while the cluster was running.