I have a HA auto failover SQL 2005 mirroring setup in my production environment, and I need to move the witness instance from Server A to Server B.
Is it as simple as changing the witness address location in the mirroring section on the principal server?
This is a production DB so I want to make sure that changing the witness doesn't take the database offline.
Any links, tips, personal experiences would be greatly appreciated
According to this Database Mirroring Best Practices and Performance Considerations article mirroring continues to work even when the witness fails (or as in your scenario it is taken offline and is replaced by another witness server). The same would be true if you SET WITNESS OFF.
But I would test this in a non prod environment, alternatively get someone to hold your hand during the switch if you're not 100% certain...
Loss of the witness If the witness server fails, database mirroring continues functioning without interruption, except that automatic failover is not possible. Once the witness becomes operational, it automatically joins the database mirroring session.
The problem in my situation was that I did not know that all, the witness, the principal and the mirror's SQL Service account at the Windows Services level should be running under the same domain account. All three need to be under the same domain. Once that is done, the Witness server can be easily changed.
Also, mirroring is obviously possible even in different domains and with different names. You have to have the logins defined in each SQL and have the CONNECT privelages granted properly before you do this.
I have marked this solution as a community wiki incase someone needs to add/modify some of what I said.
answered Aug 23, 2011 at 11:52 AM