SUMMARY: Fujitsu 1.2Gb disk on Sun (and DEC)

[Ross Parker]

In an attempt to stem the flood of responses to my query
(*not* that I'm complaining!!! :-) I'm summarizing what
I've found out about 1.2Gb disks and Sun (and DEC) systems.

First - There's a firmware bug on the Fujitsu M2266 drive
that makes it imperitive to disable the drive's read-ahead
cache (jumper 5-6 on bank CN3/CN9). Fujitsu is apparantly
distributing upgraded proms (to their distributors... contact
the vendor you bought the drive from) that fix the problem.
This problem is only apparant on Sun systems, and causes a
large number of read errors on the drive.

Second - There's a problem with the M2266 being on a SCSI bus
with other devices. We've found that if the drive is on a
bus with tape drives (either 1/4" or exabyte), the drive must
be first on the bus. This might be linked to termination in
some way, though others have had the same problem.

Third - When the drive is formatted, parameters must be
carefully chosen to keep the addressing within SCSI-1 limits.
For the M2266, this means formatting with 1642 data cylinders,
2 alternates, 15 heads, 85 sectors/track. This is 16 cylinders
short of the full disk capacity. We did have this information
direct from Fujitsu when we installed the disk initially.
This limitation works fine on a Sun. Apparantly, however,
DEC systems wrap around when they reach high sector addresses,
and scribble on the beginning of the disk. This happened to
us last week (with a different M2266 drive) on a DECstation
5000 - we'd attributed it to another cause, but it caused us
some grief.

Apparantly, DEC will extend their addressing with Ultrix 4.2,
and I've heard rumours from Sun tech support that there's a
patch available for SunOS that allows the same support in
SunOS 4.1.1.

Also, contrary to what some people have reported, the drive
*does* work fine in synchronous mode on a SPARCstation 2 (and
on a 1+ as well). The problem some people have seen with
synchronous mode might be related to the SCSI bus ordering
(the second point above).

I hope this clears up some of the questions that people had...

-- 
Ross Parker			| Why do they put me down?
				| Make out that I'm a clown?
parker at mprgate.mpr.ca		| I drink scotch whisky all day long
uunet!ubc-cs!mprgate!parker	| Yeah I'm gonna save my money
				| (gonna put it all away...)
(604)293-5495			| 'Cause I'm a Scotsman