Maxtor XT-8760S Mac SCSI disk on SLC

[Josh Littlefield]

Has anyone had experience connecting a Maxtor XT-8760S disk to an SLC (or
other SUN)?  The disk I have is sold by Rodime for use with Macintoshes.
I'm having 2 levels of problems: geometry and termination. 

Geometry:

First, I set the SCSI ID to 3 and connected the disk and everything seemed
fine.  Using the PROM "probe-scsi" command, it identified itself as a
Maxtor XT-8760S (which is somewhat more than there doc. told me).  I found
an unsupported (read: commented out) entry for this disk in the OS 4.1
format.dat file, which I figured I'd use.

When I tried to format the disk I got an error which the doc described as
the controller objecting to the "Page 3 Mode Select" command.  Neither Sun
nor Rodime was able to pinpoint the objection.  While I could format the
disk on a Mac, I felt it would be better to format on the Sun and be sure
of the number of formatted cylinders, etc.

After some digging (and I mean deep) I found I could go into adb and stuff
a non-zero value into a global variable to enable debugging info in
format.  This printed out each of the SCSI mode select commands and their
parameters, as well as what I assume to be the defaults indicated by the
controller.  I found when I changed the number of sectors/track from 54 to
53, the controller was happy.

But now I'm left dreaming up the partitioning stuff myself.  Anyone know
what the goals of this should be?  Anyone know why most disks with, for
example, 1632 cylinders only format 1614 cylinders with 2 aux cyls?
Anyone know if this Maxtor really has only 53 sectors/track?

** Rodime just called back (after >week) and said the disk has a variable
number of sectors/track -- varying from outside to inside.  What does this
mean for the OS?  Is this a problem?

Termination:

I found when I daisy-chained a tape drive (brand new Archive 150 Sun 1/4")
between the SLC and the disk I got occasional errors:

	esp0:      3.0 data transfer failure
	   Stat=0x10<XZERO>, Intr=0x10<BUS>
	   Last state='UNKNOWN', Last cmd='dma tran_info'
	   DMA addr=0xff06b000, last=0xff069000;Dma CSR=0x8

	   Mapped Dma Space:
		   Base = 0xff069000 Count = 0x2000
	   Transfer History:
		   Base = 0xff069000 Count = 0x2000

These seemed related to writing to the disk, but not every write.  The
Maxtor has internal termination (yes, I double checked).  I am told by Sun
hardware support that the SLC provide term power.  After a few of these I
power cycled everything, and was able to dump my entire disk to tape.  But
on attempting to restore, I continued to get these errors, and SCSI resets
and restore kept crapping out.

** Rodime finally admits to jumpers for term power options.  I'll  play
with these.  I assume I want no term power from the disk if the SLC
supplies it?

Any recommendations?

Josh Littlefield					Cayman Systems, Inc.
							University Park at MIT
josh at cayman.com 					26 Landsdowne Street
(617) 494-1999  					Cambridge, MA  02139