info needed: IPI disk

[Ed Arnold]

Having received conflicting information from Sun and 3rd party vendors,
we're looking for someone out there who knows something about the IMPRIMIS
(aka CDC/Seagate) IPI disks sold by Sun for the 4/490, as well as
3rd-party alternates.  If you have info, please e-mail me; I will
summarize to sun-spots.

What I've been trying to find out is what disk drive is Sun selling as
their 706A/707A disk unit.  I've been variously told by third party
vendors that this disk is a CDC-97209-12G, CDC-97229-12G, and a
CDC-97200-1230.  About half of the vendors swear that the CDC-97200-1230
is the SMD-4 version.  I'm inclined to believe these vendors because
they've sounded more knowledgeable overall.  This leaves the CDC-97209-12G
and the CDC-97229-12G.  These are supposedly IPI-2 disk drives with a 1.2
Gbyte unformatted capacity.  The CDC-97209-12G is supposedly a
single-headed drive, and the CDC-97229-12G is supposedly a dual-headed
drive.  Finally, everyone seems to agree that the ISP-80 (408A/409A)
controller that Sun sells is manufactured only by/for Sun.

The greater unknowns follow.  Namely, is Sun selling the CDC-97209-12G or
the CDC-97229-12G as the 706A/707A.  The apparently knowledgeable third
party vendors seem to be evenly split on this matter.  They also are split
on whether Sun has an exclusive right to sell the CDC-97229-12G.  Some
claim only Sun and certain OEMs are allowed to purchase these disks, and
others claim certain smart VARs with superior contracts prior to the Sun
exlusive contract can also purchase these disks.  One vendor told me that
the third party sellers of the 97229 have to be purchasing their disks
from the OEMs.

Another matter concerns mounting hardware.  Only a few of the vendors
seemed aware that the new Sun Data Center Server tower-style cabinets
require mounting hardware different from the 19" racks.  Only one said
they would be able to supply this hardware.

Our local Sun rep has been unable to shed much light on the matter.  He
swears that the 706A/707A disks are single-headed models and have only a 3
Mbyte/sec transfer rate.  He also swears he's never heard of a dual-headed
model with 6 Mbyte/sec transfer rates.  Does anyone know what's really
going on here?  Finally, how does the dual-headed model achieve
performance improvement?  Is it seen by the system as two drives with
completely separate and independent hardware paths, or is some more
sophisticated hardware and software scheme being used?

Any confirmation, refutation, clarification, and/or amplification of this
information would be appreciated.