Dell Storage with Microsoft Storage Spaces Best Practices Guide

A witness disk is used when there is a node or network communication failure where the nodes continue to operate but can no longer communicate between one another. The witness disk acts as part of the voting process to determine which nodes remain as part of the cluster to maintain quorum. Use witness disks on clusters with even number of storage nodes to ensure there is a vote majority in case of a split-brain situation.

There are two options for witness disks — disk witness and file share witness. Dell recommends you to use file share witness because a continuously available SMB share can be created on the SOFS cluster to host the witness disk. You can create the file-share witness disk on a small 3 GB, Two-way mirror VD without storage tiers.

Run the following PowerShell command to create the cluster quorum disk.

Set-ClusterQuorum <Mode> <PathToResource>

For example,

A 3x3 configuration with three Dell PowerEdge R730 storage nodes. Setting quorum mode to node majority with no file share or disk witness on cluster named MYCLUSTER.

Set-ClusterQuorum –NodeMajority –Cluster MYCLUSTER

For example,

A 4x4 configuration with four Dell PowerEdge R630 storage nodes. Setting quorum mode to node and file share majority with a 1 GB VD setup as a SOFS file share. The cluster is named MYCLUSTER and file share is named FileShareWitness.

Set-ClusterQuorum -NodeAndFileShareMajority "\\MYCLUSTER\FileShareWitness"