SCSI tape problems

[T. Horsnell]

Hi all,

I wonder if I could ask your advice about a very strange
SCSI tape problem I'm having. I have an Overland Neo2000
tapelibrary containing dual Quantum SDLT2 drives, attached
to a dual Opteron box via an Adaptec 3920 controller.
The system is running FC3 up2date'd on April 6th
and with kernel 2.6.10-1.770_FC3smp.

The problem appears to be that the tapes drop records
when being written, but that this can be fixed by increasing
the blocksize.

I have a bunch of test files filled with random numbers:
e.g.
-rw-r--r--  1 root root   500000 Apr 26 11:03 tapetest500K
-rw-r--r--  1 root root 1000000000 Apr 26 12:48 /var/tapetest1G

When I write these to tape and read them back, I get things like
the following:

[root at ls1 ~]$ dd if=tapetest500K of=/dev/st1 bs=10240 ; dd if=/dev/st1 of=junk bs=10240 ; cmp tapetest500K junk
48+1 records in
48+1 records out
36+1 records in
36+1 records out
tapetest500K junk differ: byte 215041, line 854
[root at ls1 ~]$ dd if=tapetest500K of=/dev/st1 bs=20480 ; dd if=/dev/st1 of=junk bs=20480 ; cmp tapetest500K junk
24+1 records in
24+1 records out
24+1 records in
24+1 records out
[root at ls1 ~]$ ( cd /var ; dd if=tapetest1G of=/dev/st1 bs=10240 ; dd if=/dev/st1 of=junk bs=10240 ; cmp tapetest1G junk )
97656+1 records in
97656+1 records out
90107+1 records in
90107+1 records out
tapetest1G junk differ: byte 215041, line 866
[root at ls1 ~]$ ( cd /var ; dd if=tapetest1G of=/dev/st1 bs=20480 ; dd if=/dev/st1 of=junk bs=20480 ; cmp tapetest1G junk )
48828+1 records in
48828+1 records out
48801+1 records in
48801+1 records out
tapetest1G junk differ: byte 2621441, line 10186
[root at ls1 ~]$ (cd /var ; dd if=tapetest1G of=/dev/st1 bs=32768 ; dd if=/dev/st1 of=junk bs=32768 ; cmp tapetest1G junk)
30517+1 records in
30517+1 records out
30517+1 records in
30517+1 records out
[root at ls1 ~]$ 

The problem happens on both tapedrives.
No errors are logged in /var/log/messages.
The Neo2000 system performs faultlessly when attached to my Alpha box.

Does this look to you like a hardware problem? Or could it be a driver issue?
Unfortunately I dont have enough spare kit to try things on another box.


Regards,
Terry