Strange - I've not had any problems with optical drives.
My fileserver runs a pair of mirrored data disks. For backup/archiving, I snapshot the data every night, which gives me access to the files as they were at that point. That's used to retrieve any individual files from yesterday, or any day -- as I've never yet needed to delete any snapshots, so I can recover any file at any date back over the last 2.5 years. For disaster recovery, I attach a 3rd mirror disk, allow it to resilver, and then detach and store off-site. Frequency of doing this is variable, depending on how much work I've done.