Automatic mirroing failover and application connectivity

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Automatic mirroing failover and application connectivity

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Minaz

Posted Tuesday, November 27, 2012 11:25 PM

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Hi All,

We are planning to setup DB mirroing for our prod server with automatic failover.

I need your suggestions and recomendation on the same. There were few concerns raised by the team and Iam not clear how this is handled in mirroing. On sql 2008 on window 2008

If I have setup mirroing of three DBS and if one of them goes doen or crashed. Will the crashed database will failover to mirroed server?
If yes, how the aaplication communicate to it? 2 databases will be on pricipal server and the crased db will failover to mirroed and how the application communicate with all these three DBS.

Will there be any downtime , cxoonection time out during this failover?

Please clearify my doubts.

Thank you.

"More Green More Oxygen !! Plant a tree today"

Post #1389515

Posted Wednesday, November 28, 2012 12:08 AM

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Automatic failover will happen. After this, application will be directed to new principal server(earlier it was mirrored) and will find only one database (in your case). Other two databases will remain in old primary server which will be unreachable to your application.To solve this, you have to setup a alert for failover event, and force your other databases too to failover.

Failover will result in running "recovery" in mirrored database. Downtime will depend on how much transactions to be recovered.

http://www.mssqltips.com/sqlservertip/1564/database-mirroring-automating-failover-for-multiple-sql-server-databases/

Post #1389526

Perry Whittle

Posted Wednesday, November 28, 2012 1:36 AM

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Minaz Amin (11/27/2012)

If yes, how the aaplication communicate to it?

If you're using ADO.NET or SQL Native client there is a "Failover Partner" option specifically for database mirroring sessions

Minaz Amin (11/27/2012)

2 databases will be on pricipal server and the crased db will failover to mirroed and how the application communicate with all these three DBS.

The failover is per database, Failover clustering affects all databases on an instance

Minaz Amin (11/27/2012)

Will there be any downtime , cxoonection time out during this failover?

Please clearify my doubts.

Thank you.

Yes, as already stated it depends on the log queue that is waiting and the time to recover the database, in extreme cases it can take some time for the database to come online

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"Ya can't make an omelette without breaking just a few eggs" Wink

Post #1389564

Minaz

Posted Wednesday, November 28, 2012 10:50 PM

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Thank you all for the response. This has really helped me.

"More Green More Oxygen !! Plant a tree today"

Post #1390278

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