Backup Restrictions

In Microsoft® SQL Server™, backup operations can occur while the database is online and in use. However, some operations are not allowed during a database backup:

• Creating or deleting database files.
  
  
• The file truncation portion of a shrink operation on either the database (automatically or manually) or the database files. They will fail if a backup is running. You can perform the truncation after the backup completes. For more information, see Shrinking a Database.

If a backup is started when one of these operations is in progress, the backup waits for the operation to complete, up to the limit set by the session timeout. If a backup is in progress and one of these operations is attempted, the operation fails and the backup continues.