Maintenance on Mirroring witness server

Question

Hi

I have couple of automatic failover mirroring setups and a single host which acts as a witness for all the mirroring set up I have.

Now I am planning a maintenance window on my witness server.

I want to study the impact on my mirroring setup when my witness wont be available for sometime.

I expect only the auto failover cannot happen during the the outage on witness server and no impact to data sync between my principal and mirror.

Once the witness server is fully up after the window, the setup will be back as High synchronous with automatic failover again.

Is my assumption correct or is there any other precautions that I need to take care?

Thanks in advance.

Answer 1

Hi @udhayan d ,

Please refer to official document: Role of the Witness in Automatic Failover

I expect only the auto failover cannot happen during the the outage on witness server and no impact to data sync between my principal and mirror.

In mirroring, a witness server is not required. With a witness server, the principal and mirror databases talk to the witness server in addition to maintaining a session with their partners. There is no replica of the database on the witness server, it just acts as a neutral arbitration to establish a session with the principal/mirror server, determine the health of the database, and trigger an automatic failover to switch the roles of the mirror database and the principal database when the principal database is abnormal.

Thus, there is no impact to data sync between my principal and mirror. In addition, you can focus on Mirroring States (SQL Server)

Best regards,

Seeya

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