FileShareWitness disappeared and all databases dismounted

With three mailbox servers, the File Share witness is not used. ITs for DAGs with an even number of mailbox servers.

Hi @Innocent Heartvoice ,

Welcome to the Microsoft Q&A platform!

Based on your description, you are experiencing issues with the File Share Witness (FSW) in a Database Availability Group (DAG). When the FSW or quorum disk is unavailable, the DAG loses quorum, causing all databases to unmount.

Here are some potential causes:

1. Intermittent network issues between the DAG members and the FSW can cause the FSW to be unavailable.
2. Issues with the server hosting the FSW (such as hardware failure or software issues) can cause the FSW to be unavailable.
3. Incorrect configuration of the FSW or quorum settings can cause availability issues.

You can try the following methods to resolve the issue:

1. Ensure that the network connection between all DAG members and the FSW server is stable and reliable. Use network monitoring tools to identify and resolve any intermittent connection issues.
2. Check the health and performance of the server hosting the FSW. Ensure that the server is not experiencing hardware or software issues that may affect its availability.
3. If the FSW cluster resource is offline, you can bring it back online using PowerShell:

Get-ClusterResource -Name "File Share Witness" | Start-ClusterResource

This command checks the status of the FSW cluster resource and starts it if it is offline.

4. If restarting the FSW cluster resource does not resolve the issue, you may need to recreate the FSW:

Set-DatabaseAvailabilityGroup -Identity DAGName -WitnessServer NewWitnessServer -WitnessDirectory NewWitnessDirectory

Replace DAGName, NewWitnessServer, and NewWitnessDirectory with your actual DAG name, new witness server, and directory.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang

The same issue occurred again where the cluster quorum disappeared. One thing to note is that the File Share Witness file, which is supposed to be created in the file share folder, does not exist, even though the cluster itself appears to be running.

Yesterday, the cluster went down twice, and the cluster's IP address was not responding to ping. At the same time, all the databases were showing as dismounted, even though the server itself was displaying a healthy status.

The File Share Witness path was also changed, but it did not make any difference. The same issue persists, where the databases suddenly become disconnected.

One more update that one primary site and DR mailbox servers are on CU7 which were on old hardware and the One mailbox server is on CU23 which is on new hardware.

Kindly assist what should do.