startup guide
18 Appendix F: Database Mirroring
Database mirroring is a feature of SQL Server (available only in the Standard and Enterprise editions of SQL Server since SQL Server 2005 SP1) that provides high-availability without the need for a single-copy cluster.
To use mirrored databases with PureMessage, you must perform the following:
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Prepare SQL Server instances
(page 43)
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Install PureMessage with database mirroring
(page 44)
Configure PureMessage for database mirroring
(page 44)
18.1 Prepare SQL Server instances
Before installing PureMessage, you must prepare the SQL Server instances that will be used. A mirrored SQL database requires two or three SQL Server instances:
1. A principal server instance (data source).
2. A mirror server instance (failover partner).
3. Optionally, a witness server instance.
For information on SQL Server preparation for mirroring, see: http://www.microsoft.com/technet/prodtechnol/sql/2005/dbmirror.mspx
http://msdn.microsoft.com/en-us/library/ms190941.aspx
Note:
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Ensure that the SQL Server instances are authenticated to access each other. This means that the accounts under which a SQL Server instances run must be granted access to the other SQL Server instances used in the mirror set, and that remote connections (e.g. over the
TCP/IP protocol) must be enabled.
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The principal and mirror server instances should host the same edition of SQL Server, and it should be an edition that supports mirroring.
For automatic failover, a witness server is required.
For high-availability, the SQL Server instances must be installed on different physical servers and use synchronous mode.
If any firewalls exist between the SQL Servers, they must be configured to allow the SQL servers to communicate over the TCP port chosen for mirroring.
It is recommended that SQL installations use the same SQL instance name and file paths on all servers.
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