I've finally gotten our backups running consistently and correctly. The raid controller and SCSI controller for the tape drive are seperate, so there's no conflict there, and we're getting roughly 300 MB/min xfer to tape. Not blazing fast, but with an ADIC 228 and DLT7000, that's more than adequate since we can duplicate to tape in the down time.
Xfer speeds are identical regardless of whether the tape device is backing something up concurrently with B2D taking place or not, and the fragmentation disparity between a standard sata single drive and the raid-5 array is a scale of 20,000/1, 20,000 fragments being the raid 5 to each 1 fragment on regular single drive.
I'm going to be running a test server with onboard h/w Raid-0 on some older hardware to see if raid-0 suffers the same fragmentation as raid 5 seems to, and also take a look at running that same hardware rig respun w/out raid, assuming raid-0 has the same fragmentation problems.
With our NAS getting 6MB/sec writes, 30 MB/sec reads, and Veritas dropping a 1 gig file in 40,000 fragments, it's no small wonder the machine takes a long time to write to disk. As for defragmenting the volume, I've been working on that nightly with winternal defrag for ~6 hours daily, and it's reduced the drive fragmentation from 99% roughly down to 96%. Not much I can do there.
~Josh
