Possible Exabyte problem with DS3100
Paul Coppi
coppi at karl.tapir.Caltech.EDU
Sun Oct 15 20:00:54 AEST 1989
Hi,
We recently acquired a DECstation 3100 with an 8mm Exabyte tape drive.
Unfortunately, we cannot get the Exabyte to work satisfactorily.
The tape drive can reliably read in data from tapes written on Exabytes
connected to other machines (Sun 3,4s), but it appears to drop bytes
when trying to do a write. Specifically, a byte appears to be
dropped every 200-500k of output. The exact locations of the dropped
bytes appears to be random. (Repeating exactly the same sequence of
commands, the errors occur in different places.) No error messages
show up while doing the write, but the file on tape is definitely corrupted.
Tar, for example, will give checksum errors when you try to read
the file back in. I have also done a dump straight to the
device using "cat bigfile > /dev/rmt0h". Reading the file in
with "cat < /dev/rmt0h > bigfile.out" and doing
a "cmp -l bigfile.out bigfile" gives the same answer (the files differ)
when the Exabyte connected to the DECstation is used or an
Exabyte connected to a Sun is used. I've tried this with several tapes
(in case one of them was bad).
We have reported the problem to our vendor (Computer Systems Technologies
in El Toro, CA), but they didn't have anything useful to say.
Any ideas?? We would like to know if someone else out there is using an Exabyte
to write large files and has experienced similar problems. Could you
please tell us exactly what your system configuration is, what ROM revision
level your Exabyte is (if your machine is halted, you can print it out
by typing "test -c<ret>" after the console monitor prompt ">>"),
and what programs you have successfully/unsuccessfully
used your Exabyte with. Does any one know of a preferred blocking
size for the Exabyte? It could well be that our drive is faulty.
(If we get lots of "Yes, our Exabyte works" responses, we'll ship
ours back to the vendor.) However, given the problems people have
had getting Exabytes to run with Suns, something deeper may be wrong.
Our system configuration is as follows: 1 12 MB DS3100, 2 CDC WREN V
disks, 1 Exabyte with ROM revision level 4.24. We are running Ultrix
3.1, and the Exabyte is recognized as SCSI device #4, type "TZxx".
Thanks in advance for any help you might be able to give,
Paolo Coppi
Theoretical Astrophysics, Caltech
coppi at tapir.caltech.edu, coppi at zeppo.caltech.edu
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