Most web hosting providers do not allow customers to use server space for storing file backups and there have been instances where personal files were deleted from the server without any warnings.
Now to save your personal files like music, photos or videos on Dreamhost servers, you’ll need to create a new FTP user that is only to be used as an off-site backup - you cannot have websites associated with this ‘backup’ user.
Dreamhost gives 50 GB of disk space for your personal files and in case you exceed that limit, the cost is about 10¢ per GB per month.
Something important here - Dreamhost won’t keep a backup of your backup so please do not consider this option as a replacement of say, Mozy, Carbonite or Amazon S3. It’s just another safe-house for your files and sort of a guarantee that your web host won’t delete the personal files.
Also see: Do Not Depend on Free Storage Services