[comp.sys.sun] Attaching non-sun SCSI drives to a SparcStation

gert@fwi.uva.nl (Gert Poletiek) (11/21/89)

We are trying to hook up SCSI drives not bought from Sun to our
Sparcstations. Reason: we can buy between 2 and 3 times more disks this
way.

The problem we encountered is the following. During the last phase of
formatting the disk (a CDC Wren IV) the disk label and backup label are
written to the disk. The label is written correctly (since it is written
onto one of the first blocks of the disk), but writing the backup label
fails. We get a SCSI error back from the disk saying that the format
program tried to write beyond the end of the disk.  We tried changing the
format parameters in /etc/format.dat but that didn't help either. If
nsyl=x, acyl=y and pcyl=x+y we always get 'No media error on cylinder x'
once the backup label is being written.

We've experienced the same problem with other SCSI disks with an embedded
controller. Sun disk with ESDI/SCSI convertor boards in them do not have
this problem.

I reported this problem to Sun in Holland and they told me: Sun ships its
own CDC Wren disks.  They couldn't tell me what Sun had changed with
respect to the 'normal' CDC Wrens. The only thing they could have changed
is the ROM on the embedded SCSI controller board.

Does anyone have a solution to this problem?

khb@sun.com (12/08/89)

In article <3246@brazos.Rice.edu> it is written:
>X-Sun-Spots-Digest: Volume 8, Issue 205, message 5 of 19
>
>The problem we encountered is the following. During the last phase of
>formatting the disk (a CDC Wren IV) the disk label and backup label are
>written to the disk. The label is written correctly (since it is written
>onto one of the first blocks of the disk), but writing the backup label
>fails. We get a SCSI error back from the disk saying that the format
>program tried to write beyond the end of the disk.  We tried changing the
>format parameters in /etc/format.dat but that didn't help either. If
>nsyl=x, acyl=y and pcyl=x+y we always get 'No media error on cylinder x'
>once the backup label is being written.

I'm no SCSI wizard, and the following information should be considered
pure hearsay, and not attributed to me or to sun.

When I did peek at some scsi problems, I found that there were serious
problems with the ROM/firmware the vendor provided (_not_ CDC). Coding
around those errors was a major hassle. Fortunately, I managed to get
removed from that task :>

If Sun provides SunROMs, I'd bet that there are bugs in the CDC firmware.
These can be coded around/may correspond to matching bugs on other systems
.... but someone decided that the proper fix was to fix the disk. Of
course, CDC reserves the right to ship crock for crock buggy drives to
everyone else ... 

Note that I'm not in an I/O group, I'm a compiler/applications/performance
weenie, and I'm speaking for myself, bymyself and do not represent Sun in
any way on this.

The marketing critters may have much more entertaining (and possibly
correct) stories.

Keith H. Bierman    |*My thoughts are my own. !! kbierman@sun.com
It's Not My Fault   |	MTS --Only my work belongs to Sun* 
I Voted for Bill &  | Advanced Languages/Floating Point Group            
Opus                | "When the going gets Weird .. the Weird turn PRO"

mjacob@sun.com (Matt Jacob) (12/08/89)

In article <3246@brazos.Rice.edu> gert@fwi.uva.nl (Gert Poletiek) writes:
|X-Sun-Spots-Digest: Volume 8, Issue 205, message 5 of 19
|
|The problem we encountered is the following. During the last phase of
|formatting the disk (a CDC Wren IV) the disk label and backup label are
|written to the disk. The label is written correctly (since it is written
|onto one of the first blocks of the disk), but writing the backup label
|fails. We get a SCSI error back from the disk saying that the format
|program tried to write beyond the end of the disk.  We tried changing the
|format parameters in /etc/format.dat but that didn't help either. If
|nsyl=x, acyl=y and pcyl=x+y we always get 'No media error on cylinder x'
|nce the backup label is being written.
|
|We've experienced the same problem with other SCSI disks with an embedded
|controller. Sun disk with ESDI/SCSI convertor boards in them do not have
|this problem.
|
|I reported this problem to Sun in Holland and they told me: Sun ships its
|own CDC Wren disks.  They couldn't tell me what Sun had changed with
|respect to the 'normal' CDC Wrens. The only thing they could have changed
|is the ROM on the embedded SCSI controller board.
|
|Does anyone have a solution to this problem?

The CDC-WrenIV that I worked with for SS-1 was the model 94171-344. The
format.dat entry as supplied with SS-1 worked with that. Please remember
that since the CDC Wren-IV is a variable geometry drive, the ncyl, acyl
and pcyl values are constructs, so that if you change /etc/format.dat to
what you think *might* be a better value, you may be disappointed.

You aren't running with beta code are you? There was a bug that I think
that we fixed last spring where the sectorss/trk field was being set for
variable geometry drives (this had an unpleasant side effect of truncating
about 10mb off of the end of the disk).

Another thing- if the drive is seen w/o a label, on SS-1 it will print the
vendor string and the drive's reported capacity- this might be a clue as
to what is going on (like, the drive is reporting significantly less
capacity than it should have).

-matt jacob