backing up media drives using Time Machine
Is it practical to use time machine to backup a large media drive array to a 2nd drive array?
I'd love to use Time Machine to back up a 2nd Mac's media drive array as well to this same 2nd drive array. The two Mac's are both connected by a 2GNetwork so through sharing, we can see each others' drives. I don't know how time machine works but assume it is actually doing a complete backup and then incremental daily backups? If so then the backup drive needs to be considerably larger than the drives it is backing up? Can one use an LTO or DLT drive instead?
I am currently backing up my 6TB media drive array once a week or so by using Intego Backup software by synchroning it to a 2nd 8TB drive array which is normally left off. I am using Time Machine to backup my boot drive to a 2nd internal drive. This is time consuming and not done as frequently as it should be because it isn't automated.
Time Machine is an excellent method for backing up. As you mentioned, it does one complete backup, and then incremental backups. It's extremely easy to set up (like most things Apple), and you can exclude things you wont backup like cache etc. I back up everything using TM. There are a few things you might want to be aware of:
As far as I know, you can only backup to one drive (raid or whatever). This means all your data will be backed up to the "TM Drive". I backup both my system drive, and a software raid0 to another software raid0, via SATA at 500MB/s (according to Activity Monitor). The important thing to remember is that if you want to restore your system drive, it can't be done from anything else, than drives connected via Network, FW, USB og internal SATA. Aka if you use an external raid for backup of your sytem drive, make sure you can access the raid when booting from the OSX DVD! In my case, all my external drives for the TM raid, have FW800 connectors I can use in case of an emergency. Hope this makes sense. It is important to understand this issue before using a raid as your TM drive!!!
Time Machine needs some overhead to index files etc. This means you cannot backup 6TB data to an 6TB raid. Since TM does incremental backups, your backup size will increase over time. A trick is to disable backup of some directories, during initial backup, and then enable them again, for incremental backup afterward.
All in all, once you've setup TM, it pretty much just does the job, without headaches and with a history of your drives, in one hour increments. Nice ;)
Mac Pro 2008 8-core.
Macintosh HD: 2x 120 GB OCZ Vertex2's in Raid0
Media raid: 6x 1TB Samsung F3 in raid0. 2 drives in internal drive bays and the rest on a Sonnet E4P eSata contr. (770 MB/s sustained RW from a cheap software raid!)
TM Drive: 4x 1TB Samsung F3 in raid0 on another Sonnet E4P.
Storage: 3x 4TB WD Mybook Studio, each mirrored down to 2TB with WD Drive manager, and striped in Disk Util (Raid10), connected via FW800. (No TM backup).
Hope this helps :)