There’s not very much information online about using a IBM TS3200 (3573-TL) SCSI tape library with the “mtx” utility, and the documentation for the library doesn’t mention much about Linux at all. I’m using rdump, over SSH, and I’ve reached the end of tape. As I understood it, the tape library was supposed to automatically load the next tape in sequence. It did not, so I attempted to do move on to the next tape manually, using “mtx next” or “mtx unload”, both giving the same error: *(See update at the end).

Unloading Data Transfer Element into Storage Element 1…mtx: Request Sense: Long Report=yes
mtx: Request Sense: Valid Residual=no
mtx: Request Sense: Error Code=70 (Current)
mtx: Request Sense: Sense Key=Not Ready
mtx: Request Sense: FileMark=no
mtx: Request Sense: EOM=no
mtx: Request Sense: ILI=no
mtx: Request Sense: Additional Sense Code = 04
mtx: Request Sense: Additional Sense Qualifier = 8E
mtx: Request Sense: BPV=no
mtx: Request Sense: Error in CDB=no
mtx: Request Sense: SKSV=no
MOVE MEDIUM from Element Address 256 to 4096 Failed

According to IBM’s somewhat hard to find information, the error code 70 does indeed mean “Current” as mtx indicates. The sense key means “Hardware error”. The doc references the TSM Appendix C to determine the “Additional Sense Qualifier”, but the information is not actually contained there. I remain unsure exactly what it means. There’s some indication on non-IBM sites that it means the library is in sequential mode (which it is) and that the software needs it to be in random mode. I dunno, random mode doesn’t make a lot of sense to me.

In any case, this error is pretty far from “clear”. I hope this information helps someone in the future. The mtx man page indicates: “You may need to do a ‘mt offline’ on the tape drive to eject the tape before you can issue the ‘mtx unload’ command.” With this library and its autoload configuration, you do indeed need to run “mt offline” and then it will automatically load the next tape in sequence.

Now if only I could figure out why it gives the same errors above when I run “mtx first” or “mtx load 1″ or even “mtx transfer 1 21″ then I’d be set. All of that worked in the past (as in a couple of days ago). Does everyone just use backup management software to handle all of this nowadays? Are we the last “dump” holdouts? I’ll update this post if I figure out a reliable way to use this library with Linux — the last thing we need is more pages with more questions than answers online, and here I go posting one of those. :)

Update: Yes, the library needs to be in random mode to use mtx’s “next” “load” and “unload” commands. Random mode basically means “fully manual” mode, which is exactly what I was hoping to have. Sweet. As far as backup speed is concerned, we’re pushing 230Mbit/s with xfsdump over rsh/ethernet, which isn’t quite up to the drive’s rated speed, but it’s the max we’ve been able to get.