Hi Alex,
Has this backup always run at this speed? If my calculations are right, it's running at about 200-300 MB/min. Definitely too slow for an Ultrium tape drive. From what you describe, you're not running a backup over your network, so messing with the NIC settings will not have any effect, but restarting the tape drive could help, as well as cleaning the drive. I would also reboot the server itself. In my experience this seems to do wonders for servers that start backing up at 10% of their normal speed all of a sudden.
If none of that works, then you're going to have to eliminate each variable until you find the culprit. I would begin by swapping out the SCSI cabling as well as the terminator (if you're using one, the Ultrium drives are self terminating if you only have one device attached to the SCSI controller). Next I would swap the SCSI controller card. If you're still having performance issues after this, start looking at the server itself. Try backing up using a different backup utility (such as the NT Backup utility native to Windows). You can also download and run the IBM Tape Diagnostic Tool to test the speed of the drive. I recommend using the GE version as it's easier to use than the SE.
http://www-01.ibm.com/support/docview.wss?uid=ssg1S4000662
Let me know if your issue gets resolved.
