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Newsgroups: comp.sys.sun,comp.periphs.scsi
Subject: Why Buy I-P-I?  SCSI is equally fast and 40% cheaper
Keywords: Hardware
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Date: 10 Apr 90 20:28:56 GMT
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[For 1.2 GB, 3Mbyte/sec or 6Mbyte/sec transfer rates, 16-18ms average access]

> The lowest prices we've heard of for the 97209-1230 and 97229-1150 have
> been ~$6800 and ~$11500, respectively.

I have found two synchronous SCSI drives in the same performance range,
with much lower prices.

The Imprimis Wren-7 is a 1.2GB drive with a sub-20ms average access time
and up to 4MB/sec synchronous SCSI transfer rate.  Hewlett-Packard also
makes a 1.2GB SCSI drive with 16ms average access time, 4MByte/sec
transfer rate synchronous, 1.5MByte/sec asynchronous.

The Imprimis drive (without power supply or cabinet) is available from
Arrow Electronics for ~$4000.  The HP drive is available from Hybrid
Systems (+1 617 357 1838) for $4150.  It comes with a 5-year warrantee
from HP.  Besides the benefit of a 40% price reduction, these are 5-1/4''
drives, taking trivial space and power and not requiring rack mounting.
(Hybrid can also sell you the Imprimis drive, and packaging and cables and
such.)

The SPARCstation-1 supports synchronous SCSI under SunOS 4.0.3c.  You have
to enable it by patching the kernel flag word "scsi_options"; see
/usr/include/scsi/conf/autoconf.h.  It is disabled by default because old
SCSI cabling is not high enough quality to run sync SCSI, and Sun didn't
want customers seeing error when cabling up old shoeboxes and such.  (The
kernel recovers and turns off sync scsi, but if the failing operation is
on a tape drive, it is hard to recover from.  Disks just retry it async.)

I'm fuzzy on this, but I think the 3/80 has the same SCSI hardware, but
its kernel enables sync scsi by default, due to different teams making the
decision.

None of the Sun VMEbus SCSI host adapters support sync scsi, as far as I
know.  I have a SCSI-3 adapter and it does not.

My HP drive is "in the mail" and I can let you know how it works in a few
weeks.  I've had nothing but pleasure from my two Imprimis Wren-5's so I
expect that a Wren-7 would do fine too.  It was the 5-year warrantee from
HP that swayed me in their direction.

I don't know of any SCSI drives that have hit the 6MB/sec transfer rate of
the $11500 IPI drive (the one Sun doesn't sell, though their salesmen talk
big about the superior transfer rate of IPI drives over SMD and SCSI).
But for that money you could buy TWO 1.2gig SCSI disks and TWO host
adapters, for a similar aggregate data rate but twice the access arms,
twice the capacity, and the ability to transfer data on one drive while
the other is seeking.  (Yes, Virginia, you can plug multiple SCSI host
adapters on S-bus cards into the SPARCstation-1.  I've run into some
people who didn't even know it had a bus!)

	John Gilmore