Tuesday, March 27, 2012

DR Scenario

For High Protection mode (2servers, no witness, FULL safety), in the event of a catastrophic failure of the principal, can a remote (but well connected) mirror be forced to assume the principal role? The MS manual "Database Mirroring in SQL Server 2005" on p2 says the failover type for HP mode is manual only (as opposed to forced). Elsewhere it seems to seems suggest otherwise but there is no clear and unambiguous discussion describing the exact procedure.

Can anyone clarify this matter? Thanks,

Bud

Since posting this question I have found in the May 2007 SQL 2005 Books On Line a clear statement that the mirror server in the above scenario can be forced to the principal mode.

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Bud,

In high protection mode the failover is Manual. As no witness server is available automatic failover is ruled out. So the manual failover is done as follows,

1.either clicking the Failover button in the Database Properties/Mirroring dialog in SSMS or

2.ALTER DATABASE DBNAME SET PARTNER FAILOVER

once it is done the mirror server will become the principal server.

refer, http://sql-articles.com/articles/dbmrr.htm

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Bud

Just to add. Your statement stated that you can FORCE a failover. In High Protection you dont need to force a failover because the data is in sync. You only force a failover in High Performance mode using the

ALTER DATABASE <database> SET PARTNER FORCE_SERVICE_ALLOW_DATA_LOSS

because the data may not be in sync and you are accepting the loss.

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