How to configure GlusterFS server quorum

Server quorum in GlusterFS protects volume configuration and cluster metadata by requiring a minimum number of servers to stay online before changes are accepted, reducing split-brain risk during partitions and outages.

Server quorum is controlled by the cluster.server-quorum-type and cluster.server-quorum-ratio options, which glusterd uses to evaluate quorum membership across the trusted pool. When quorum is not met, management operations are restricted and brick processes can be stopped to avoid serving potentially stale state.

Two-node pools are especially sensitive because any ratio above 50 effectively requires both nodes to remain online, which can remove practical failover. An odd number of servers or an arbiter-based design is typically needed to keep quorum protection without turning a single-node outage into a full service interruption.

Steps to configure GlusterFS server quorum:

List available volumes to choose the target volume name.
```
$ sudo gluster volume list
volume1
```
Replace volume1 with the chosen volume name.

Enable server quorum by setting cluster.server-quorum-type to server.

$ sudo gluster volume set volume1 cluster.server-quorum-type server
volume set: success

Set the server quorum ratio for the trusted pool by setting cluster.server-quorum-ratio to 51.
```
$ sudo gluster volume set volume1 cluster.server-quorum-ratio 51
volume set: success
```
On a two-node trusted pool, setting cluster.server-quorum-ratio above 50 requires both nodes to be online, or brick processes may stop and client I/O can fail.

Verify the server quorum type setting.

$ sudo gluster volume get volume1 cluster.server-quorum-type
Option                      Value
------                      -----
cluster.server-quorum-type  server

Verify the server quorum ratio setting.

$ sudo gluster volume get volume1 cluster.server-quorum-ratio
Option                       Value
------                       -----
cluster.server-quorum-ratio  51