'''Problem:''' Backing up a system that keeps its state in multiple files can be a problem, and can result in a backup that restores the system to an inconsistent state.

'''Example:''' Database systems that use separate files for tables and indices. If the files change between the time that the backup process archives them, the archive will be inconsistent. Source-code control systems that use multiple physical files might also be vulnerable.

'''Therefore:''' Before you depend on their being reliable backups for a system you depend on, verify whether the system needs to be quiesced before being backed up, or has its own backup procedure. Have someone RTFM, and/or contact the vendor. 

You might get (un)lucky and miss this if you do a DryRunBackup.
--DaveSmith