I was troubleshooting the gremlins (more on that later) in a system with a new LTO2 tape drive attached to the system. The drive was detected on boot, /dev/tape symlinked properly to /dev/nst0, "cat /proc/scsi/scsi" showed the device and finally "mt status" properly queried and returned information on the drive. However when I actually went to write data to the device it would give an Input/output error. Further investigation into dmesg gave this error:
st0: Error with sense data: <6>st0: Current: sense key: Aborted Command
I won't go into the troubleshooting steps and go straight to the resolution. The Adaptec card in the system (specifically the 39320D) by default configures all SCSI IDs for 320MB/s transfer, go into the bios and change the transfer speed to 80MB/s. When you do this some other options will change, don't worry about that. Next change "Enable Disconnect" to "no". After you do this you should be able to read/write to the drive without problems.