Quorum witness for a 3 node cluster

Question

I have a 3 node Windows Server 2016 DataCenter Failover Cluster with a SQL Always On Availability Group (SQL Server 2019) with no shared storage.

There are two nodes in Site1 and a third node in another remote site Site2.

Is a file share witness the best option for as a quorum witness?

Does it matter which site should the file share witness be placed in?

Does the file share witness have to be Server 2016 and up?

Also, what would happen if the file share witness server was to go offline in the above setup?

Answer 1

Hey,

It is recommended to have file share witness to run on a separate location from the cluster workload. In this scenario cluster nodes will have connection to the Witness regardless site-to-site network communication.
https://learn.microsoft.com/en-us/windows-server/failover-clustering/manage-cluster-quorum

As an alternative, you can deploy StarWind VSAN HA LUN to run as a witness disk between your sites. Might help:
https://www.google.com/search?client=firefox-b-d&q=stariwnd+2+node+hyper-v

Cheers,

Alex Bykovskyi

StarWind Software

Note: Posts are provided “AS IS” without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose

Answer 2

Hi @AlexJohn-9084,

Is a file share witness the best option for as a quorum witness?

A file share witness is recommended when you need to consider multisite disaster recovery with replicated storage. Configuring a disk witness with replicated storage is possible only if the storage vendor supports read-write access from all sites to the replicated storage

Does the file share witness have to be Server 2016 and up?

You can host a file share witness on a domain-joined Windows server, or if your cluster is running Windows Server 2019, any device that can host an SMB 2 or later file share.

https://learn.microsoft.com/en-us/windows-server/failover-clustering/file-share-witness#:~:text=A%20file%20share%20witness%20is%20an%20SMB%20share,to%20a%20router%20as%20a%20file%20share%20witness.

Also, what would happen if the file share witness server was to go offline in the above setup?

A file share witness is not “the quorum”, it is voting member that helps establish quorum. As a general rule, the voting elements in the cluster should be an odd number, there is an odd number of votes in the cluster, this means that the FSW can be lost, the cluster can still stay online.