Great question from Ed today in class. “Do the FSW’s need to be fault tolerant using clustering or other means? What happens if i lose the FSW server and a failure occurs?”

     Neither the witness server nor the witness directory needs to be fault tolerant or use any form of redundancy or high availability. There’s no need to use a clustered file server for the witness server, or employ any other form of resiliency for the witness server. There are several reasons for this. With larger DAGs (for example, six members or more) several failures are required before there’s a need for the witness server. Because a six-member DAG can tolerate as many as two voter failures without losing quorum, it would take as many as three voters failing before the witness server would be needed to maintain a quorum. Also, if there is a failure that affects your current witness server (for example, you lose the witness server because of a hardware failure), you can use the Set-DatabaseAvailabilityGroup cmdlet to configure a new witness server and witness directory (provided you have a quorum).

 

This info was found on this TechNet Page.. Managing Database Availability Groups

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