INFO: Content Management Server Supports SQL Server Log Shipping for Failover (322742)

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SQL Server log shipping is designed to provide a means of backup and to ensure failover protection if a system failure occurs. Log shipping works by continually backing up and restoring database logs to either a single computer that is running SQL Server or multiple standby computers that are running SQL Server.

The idea behind this is that in a failure, a database administrator can make one of the backup servers available to a CMS server. By re-running the Database Configuration Application (DCA) and pointing to the new server, the down time can be reduced to a minimum.

There are several things to consider, from a CMS standpoint, when a SQL Server failure occurs:

• Some content may be temporarily unavailable, resulting in HTTP 404 or HTTP 500 errors. These are typically a result of scripting that requires a round trip that must query the database.
• You may have to reissue Web browser authoring commands that are made at the time of the SQL Server failure.
• Actions that are taken with the Site Builder at the time of SQL Server failure can also fail and must be re-issued.
• If any long-running database transactions occur during the SQL Server failure, these tasks fail and the transactions are rolled back. This applies to both manually spawned site deployment imports and exports with the Site Builder tool and to automatically scheduled site deployment imports or exports with configured .rip and .rep packages.
• The background cleanup process is also affected by a SQL Server failure at the time of its scheduled execution. Background cleanup recovers and the process begins again during the next scheduled interval when the computer that is running SQL Server is available to respond.

Depending upon the server hardware capabilities, network infrastructure availability, and the state of the caches on the server, recovery time will vary.