Third-Party disks on PI

[Dave Olson]

If a drive manufacturer has followed the SCSI spec, and they haven't
handled some of the grey areas in a different way than the vendors
we have qualified, then the drive should work without too much of
a problem; of course it isn't supported, and if you have problems you
are on your own...

Some drives that we know have problems are Hitachi 314C SCSI (severe enough
to not work), early versions of Toshiba 156 (soft errors and bad data, due
to an unspec'ed timing being counted on), and Siemens 22XX and 44XX
SCSI drives (minor annoyances and 'excessive' noise).

I haven't yet seen the Maxtor, so I can't comment on it.  Beware of
termination and cable length issues, including stubs, if you go it
on your own as far as an expansion cabinet.  We follow the SCSI standard
as to connectors, pin assignments, etc., so there shouldn't be any
problem there.

The fx program should be able to handle setup and format on most
SCSI drives, given the constraints above.  Releases prior to 3.2
may have problems with the sizes of mode select pages, and pages that
it expected to see; in 3.2 we use the mode sense on page 3F technique
to get the supported pages and their sizes.

The CDC/Imprimis drives have definitely been the most reliable,
as well as the most Mb/$ of the drives we have looked at qualifying.

By the way, be very wary of trying to put external SCSI drives on our
older 4D models, since there were some violations of the SCSI standard
in regards to cabling; this has been fixed, but older systems need an
extensive upgrade to resolve the problem.
	Dave Olson

It's important to keep an open mind, but not so open
that your brains fall out. -- Stephen A. Kallis, Jr.