The actual backup of the SQL data for the main Unity database and, optionally, the reports database is done using the SQL services themselves.  As such the permissions to write files to the target directory are limited by the account the SQL services are running under.  If your site is using the local system account for these services then writing the SQL backup data to an off box location will fail.  Further, you are using a domain account for the SQL services but don’t want to grant read/write permissions to the off box location then the SQL backup portion will fail as well.

This is a fairly common scenario so we provided a simple mechanism to work around it.  First do the SQL backup to a local drive the move the backed up database files to the off box target using the account DiRT backup is running under and then delete the local copies of the backup files.  This is called the “two hop” method.

You can use this method by checking the “Use ‘two hop’ method for backing up SQL data” check box and then providing a local target to use.  Be sure to use a local drive where you have room enough to do the backup.  For large systems the SQL tables can be large so be sure to leave yourself plenty of room.