To restore is to load a database from a backup of that database and (if applicable) one or more backups of its Transaction log. If a database is lost or damaged, you can restore the database by reloading the most recent database backup and the successive log backups. A restore overwrites any information in the database with the backed up information. Use Arcserve Backup and the Agent for Microsoft SQL Server to perform restore operations using the Microsoft SQL Server Restore statement.
When you restore a database that is live and online, Microsoft SQL Server rolls back any uncommitted transactions that were active at the moment the restore job began. When the restore operation is complete, the database is in the same state it was in when the Backup statement for the backup used in the restore job was initiated, excluding any transactions that were active at that point.
As the data from the backup is being restored, Microsoft SQL Server reinitializes any remaining unused pages. For example, if a 100 MB database contains only 5 MB of data, Microsoft SQL Server rewrites all 100 MB of space. Consequently, it takes at least as long to restore a database as it does to create a database.
Microsoft SQL Server locks a database while restoring it, so that the database cannot be modified during the restore operation. However, users can access and modify other Microsoft SQL Server databases during this time.
Note: If a restore is attempted when you are accessing a database, Microsoft SQL Server will not allow the restore operation.
Important! By default, Microsoft SQL Server 2005 will not allow a restore to be attempted if a database is online and is using the Full or Bulk-Logged Recovery Models. To restore these databases, you must either take the database offline by performing a Transaction Log backup with the Log Tail option so that no transactions are lost, or restore with the Overwrite Existing Database and Files (“WITH REPLACE”) option. The only exception to this is an Online Torn Page Repair restore.
If a failure occurs while a database is being restored, Microsoft SQL Server notifies the system administrator but does not recover the partially restored database. You must restart the database restore to complete the restore job.
Note: If you cancel a restore job, the database may be left in a loading state and will be unusable until the restore sequence is completed. If the session that was being restored when the job was cancelled is not the first session in the restore sequence, you may have to start the restore sequence over from the beginning.
The destination database must have at least as much storage space available for it as the backed up database. The actual amount of data in the backed up database is not relevant for this requirement. To get information about allocated storage space, use the Microsoft SQL Enterprise Manager or Management Studio, or the DBCC CHECKALLOC statement. If the database is offline, then check the file sizes listed in the file tree of the Agent Restore Options dialog for that session, or in the Arcserve Database Manager view.
If you have a media failure, restart Microsoft SQL Server. If, after a media failure, Microsoft SQL Server cannot access a database, it marks the database as Suspect, locks it, and displays a warning message. You may have to drop (detach from Microsoft SQL Server) a damaged database, a process that you can perform using the Microsoft SQL Server Enterprise Manager or Management Studio.
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