Multiple Mirrors - SQLExpress Witness

  • Microsoft kb article# 930283 states (near the bottom under the file list):

    "You can run a witness server in Microsoft SQL Server 2005 Express Edition, and SQL Server 2005 Express Edition does not require a SQL Server 2005 license. Therefore, use multiple witness instances when you use SQL Server 2005 Express Edition."

    Does this mean that you should have a separate SQLExpress instance to act as a witness for each mirrored SQL Server Std or Enterprise instance?

    I get the feeling that we should have a differently named endpoint for each database instance we mirror, but documentation is scarce about SQLExpress's limitations in this area. Since Express will only support one mirrored endpoint per instance, it seems to me that Microsoft wants you to use a different instance (with a different endpoint name/port) to serve as a witness for each mirrored instance.

    thanks,

    Keith

  • As per KB, There was a bug which will not allow to add witness if the database name is same for another pair. By applying the fix mentioned in KB, you will not have above issue.

    There is no limitation that you need to have one witness for each principal-mirror pair.

  • Thanks for the reply, but it seems to me that the kb article is saying "this patch doesn't work for SQLExpress Witnesses, so you need to use multiple instances".

    Do you have multiple mirrored instances using a single SQLExpress mirror endpoint? I'm looking for confirmation that it will work with say, three instances and half a dozen databases (database names aside).

    It appears to be working properly for me with 2 instances and 4 mirrored databases, but when I try to add a third instance and a single database, I start getting 1456 errors trying to add the witness again.

    thanks,

    Keith

  • I don't have any mirroring setup for three instances. but my question is the new mirroring session has same database name as earlier pair? Since you said two are working, i am trying to see why 3rd is failing.

  • The new database does not share a name with other mirrored databases or instances. It's simply called "Test" - I wanted to test automatic roll over without monkeying with production databases.

    I notice in the logs that we received a 1474 error before the 1456 error:

    Database mirroring connection error 4 'An error occurred while receiving data: '10054(An existing connection was forcibly closed by the remote host.)'.' for 'TCP://WITNESS.it.bbe.edu:5022'.

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