I'm backing up to a Dell PV-124T autoloader with an IBM ULTRIUM-TD3 tape drive. With the default settings, the backup runs at 3 MB per minute. Based on some suggestions I found in the forums, I made some changes to the device properties: I turned up the buffer size and buffer count significantly, left the High Water Count at its default of zero, and turned off "Write single block mode" and "write SCSI pass-through mode." This causted the speed to increase to about 14 MB/s. So I tried maxing out the buffer size and buffer count, and it might have gotten a little faster, but not much. From what I've seen from other users, it should be backing up at 1000 MB/min or more, right?
Actually, the displayed backup speed always starts at more than 1000 MB/min, and quickly slows down. I assume that's a quirk in the way the software calculates the average rate, but it might give a hint as to what's going on.
I get the same low speed whether I'm backing up the computer running the software, or another computer on the network. Anyone have any ideas what could cause this?
