January 12, 2007 at 8:34 am
I was wondering what happens if the witness server goes down. Can we put multiple witness instances to watch for principal and secondary server? How to make sure that the witness server is operational at all times?
January 12, 2007 at 12:31 pm
I don't think you can use multiple witnesses for single mirroring where single witness can be used for multiple mirrorings..... read the following article...
http://www.microsoft.com/technet/prodtechnol/sql/2005/dbmirror.mspx
The witness server assists the principal or mirror in forming a quorum. If a witness server is present, a loss of either the principal database or the mirror database leaves two servers to form a quorum. If the principal cannot see the mirror server, but it can form a quorum with the witness, it can keep its database in service. Similarly, if the mirror and witness servers cannot see the principal server, and the mirror server can form a quorum with the witness, the mirror can take on the role of a new principal server.
The witness is not considered a single point of failure in a database mirroring session, because if the witness server fails, the principal and mirror continue to form a quorum. (For further information, see the topic "Quorum in Database Mirroring Sessions" in SQL Server Books Online.)
MohammedU
Microsoft SQL Server MVP
January 12, 2007 at 1:22 pm
I think I miscommunicated. What I really meant was: is it possible to create a true failover of the witness. In other words if witness1 fails, then the mirror is watched by witness2, if this one goes down, then witness3 watches the mirror, and so on.
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