Database restore in a combined stream environment.

Database backup performance can be enhanced by enabling multi-stream backup. Some database applications (Microsoft SQL Server and Sybase DBMS) require the database restore process use the same number of streams as the backup.

Multiplexing database backup streams is not an issue since multiplexing does not occur between streams of the same database backup job. You can multiplex the streams of a database backup with other backup jobs, but the number of streams used for each database backup job remain the same for restore.

The number of available streams for SQL or Sybase database restore is a concern when using Auxiliary Copy’s Combine Stream feature.  For example; you perform a multi-stream (4 streams) backup of a SQL Server database to disk. You then auxiliary copy these 4 streams using the Combine Streams option to a single tape. You cannot restore the resultant combined single stream backup job from tape without first staging it to disk. Once on disk,the SQL Server required multi-stream restore can proceed.  This process is handled automatically by Commvault software by temporarily staging the restored data in the destination client's Job Results folder.

Staging database restore date in the Job Results folder may require additional disk space. To accommodate this, you can change the location of the staging folder using the additional setting nStageFolderAuxCopyRestore.

Other than Microsoft SQL Server and Sybase DBMS databases, combining streams does not present any problems with other database applications in restoring a database backup job.