Quorum Mode - Node majority (no witness) vs Witness

I need to know if the node votes with no disk witness is best practice for my 3-node cluster, and safe?

In most cases, a 3-node cluster does not require additional witnesses and uses node majority mechanics to maintain its quorum. However, your situation is somewhat specific since the 3rd node is located in a different data center. That means that if the connectivity to that remote location is lost and one of the 2 HA nodes in Data Center "A" goes down for whatever reason (failure, patching, maintenance), the entire cluster will stop https://www.starwindsoftware.com/blog/understand-failover-cluster-quorum.

Does the shared storage referenced in that passage need to be on a separate network share, i.e., not on one of the 3 nodes?

In order to avoid the situation described above, you can set up a separate network share located on any other machine within the same Data Center "A" or use your existing two nodes and a free virtual SAN software to create a "shared-nothing" witness disk for clustering purposes https://www.starwindsoftware.com/vsan.

How can I verify if the WSFC is indeed using a witness on shared storage?

If a disk or share witness is configured, WSFC automatically switches to external witness quorum maintenance instead of node majority.

Hi @Cooper, David A. [ISS] (Contractor)

See this doc: WSFC Quorum Modes and Voting Configuration (SQL Server)

When using an asymmetric storage configuration for Always On availability groups, you should generally use the Node Majority quorum mode when you have an odd number of voting nodes, or the Node and File Share Majority quorum mode when you have an even number of voting nodes.

SQL Server exposes several system dynamic management views (DMVs) that can help you manage settings related WSFC cluster configuration and node quorum voting.

For more information, see: sys.dm_hadr_cluster, sys.dm_hadr_cluster_members, sys.dm_os_cluster_nodes, sys.dm_hadr_cluster_networks.

Best regards,

Cosmog Hong

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

(double post, removed)