SCSI tape drive problem

[Peter King]

Here's the problem: I have two SCSI tape drives on two machines,
theseus and plato. (Ancient Greek theme going here.) The tape
drives are different brands; one's a Sony, the other an HP. They 
have each started to fail. Syslog records the following for
theseus:

Feb  3 18:23:57 theseus kernel: st: Version 20030811, fixed bufsize 32768, s/g segs 256
Feb  3 18:23:57 theseus kernel: Attached scsi tape st0 at scsi0, channel 0, id 5, lun 0
Feb  3 18:23:57 theseus kernel: st0: try direct i/o: yes, max page reachable by HBA 163840
Feb  3 18:24:18 theseus kernel: st0: Block limits 1 - 16777215 bytes.
Feb  3 18:27:48 theseus kernel: st0: Error with sense data: Deferred st0: sense key Medium Error
Feb  3 18:27:48 theseus kernel: Additional sense: Write error
Feb  3 18:27:49 theseus kernel: st0: Error with sense data: Current st0: sense key Medium Error
Feb  3 18:27:49 theseus kernel: Additional sense: Write error
Feb  3 18:27:49 theseus kernel: st0: Error on write filemark.

Pretty much the same for plato:

Feb  3 18:26:50 plato kernel: st: Version 20011103, bufsize 32768, wrt 30720, max init. bufs 4, s/g segs 16
Feb  3 18:26:50 plato kernel: Attached scsi tape st0 at scsi0, channel 0, id 6, lun 0
Feb  3 18:46:59 plato kernel: st0: Block limits 1 - 16777215 bytes.
Feb  3 18:50:17 plato kernel: st0: Error with sense data: Info fld=0x2800, Current st09:00: sense key Medium Error
Feb  3 18:50:17 plato kernel: Additional sense indicates Write error
Feb  3 18:51:08 plato kernel: st0: Error with sense data: Info fld=0x1, Deferred st09:00: sense key Medium Error
Feb  3 18:51:08 plato kernel: Additional sense indicates Write error

The drives are correctly detected by the BIOS and on boot, and, as you
can see from the above, the st.(k)o module loads without any difficulty.
Apparently there is a "medium error" -- I suppose an error in the tape --
detected by the kernel. And there could be. But the problem shows up on
many different tapes, including brand-new ones (from two different manu-
facturers).

The symptoms are that the tape drives grind for a bit and then say that
there is a nonrecoverable error, so 0 bytes have been written. This happens
even when testing as root, so it shouldn't be a permissions problem.

So what could the cause be?
-- 
Peter King			        peter.king-H217xnMUJC0sA/PxXw9srA at public.gmane.org
Philosophy Department
University of Toronto			    (416)-978-3788 ofc
Toronto, ON   M5S 1A1			    (416)-978-8703 fax
    CANADA

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