I've utilized data domain previously.. I'm trying to refresh my memory now.. I know we also had similar issues with Active Directory i.e. our Disk Admins did. You also need Domain accounts running SQL services in order to write to data domain and then there is a way they add the accounts to be able to write to the share. We replaced Networker and Tape Backups at that time with Data Domain. So after a period of time backups were gone period.

We compressed backups since we had third party software to compress backups and save space.

One thing I'd say is you may not be able to know the space remaining. I know this is not our decision to go to data domain, but still we have to deal with the space issues as they may arise.

The other notable thing is speed in writing to data domain and load. Backups from all databases, SQL, Oracle or otherwise, files, Server backups etc constantly go to data domain and we may not know enough. We tried to stagger backups, and make sure atleast the biggest databases are not being backed up at the same time. So I tried to have a each server start one hour after the other. (I changed fulls for test/dev servers to Monday/Tuesday since, on weekends many full backups take place and typically only after they are written, older ones are deleted, so space consumption might be higher and then scale back.)

The good thing I saw was our disk admins were able to replicate between datacenters. So we could copy backups across datacenters whenever required.(DR and what not). Also, it can be handy to have access to all backups.

It could be a big deal to have everything duplicated. We only used to copy required backups across.