I've just experienced what appears to be an old problem with the
DS2100/3100 SII SCSI driver.  The problem seems to only show up on
certain disks - I can't replicate it with the RZ23 and RZ24 I'm
currently using, but found it on a Fujitsu "M2261S-512".  The problem
appears to be related to reading data:  corrupt data appears while
reading from a file.  This was first noticed when another person here
was trying to untar the snapshots using the Fujitsu on a DS2100.  I put
the drive on a DS5000/25 and was able to untar all the snapshot files
with no problem.  I then put the drive on a DS2100 (and DS3100 as well)
and experienced the same problem reading the snapshot files.

  It looks like the SII SCSI driver is corrupting the read data randomly
once in a while.  I haven't been able to figure out what might be
happening or how to debug it yet.  I no longer have the disk that was
showing this problem.  If I can locate a disk that exhibits the problem
and can keep it long enough, I'll try to find the problem.

  If I did a 'cp' of base.tar.gz to another file, 'cmp' would fail.  The
location of the failure appeared to be the same place for a given copy,
but a new copy would fail in another spot.  From this, I would suspect
that the 'cp' gets random failures reading the source file.  I had one
case where I had two copies of a binary from base.tar.gz that would fail
when running 'cmp' on them, but when I used hexdump to dump the
"failing" block, both files showed the same data.

  [I did see the references to disabling the clustered disk I/O in the
port-pmax archives, but I didn't get a chance to see if that changed the
problem.]

Michael

-- 
Michael L. Hitch			INTERNET:  osymh@montana.edu
Computer Consultant
Information Technology Center
Montana State University	Bozeman, MT	USA