IPI disks for Sun

Sat Apr 7 06:17:02 AEST 1990

This is a summary of information I received from a sun-spots request I
made about IPI-2 interface disks for Sun a while back.  I was inquiring
about what Sun was actually selling under their 706A/707A options in the
price book, and what 3rd party sources were offering.

The line of disks Sun is currently selling for 4/490 systems are from
Imprimis Technology of Minnetonka, MN (formerly owned by CDC; now owned by
Seagate).  The Imprimis "Sabre" line of 8" disks with data transfer thru a
single head at a time, consists of the 9720-368, 9720-500, 9720-736,
9720-850, and 9720-1230, where the number after the dash indicates the
number of megabytes, unformatted.  These drives have either 7 or 9
platters, TPI ranging from 960 to 1289, BPI ranging from 14981 to 25264,
and average seek time of 18 or 16 ms.  Sun's 706A option from their 1 Jan.
1990 catalog, is a 9720-1230.

(IPI-interface disks are also being offered by Fujitsu, Hitachi, and NEC,
but I have no information that Sun will accept those on their maintenance
contracts.  Besides, you want to Buy American, right?	:-) )

For increased capacity, there is a new double-density model, the
9720-2500.  One contact claims that this drive has a slightly better
average seek (i.e. < 16ms).  However, we have not been able to get any
literature on it and have not found any vendors who are stocking it yet.

For increased transfer rate, there is a dual-head-transfer model, the
Sabre 2HP 1150, which will transfer data simultaneously thru 2 heads at a
time.  This is *not* a dual-actuator drive; all heads are tied to one
actuator.  Although one contact says his Sun salesman told him that Sun's
707A *is* this drive, *our* salesman has told us that the 707A is just the
same as 706A with mounting hardware added, and that's what the 1 Jan.
1990 catalog shows; price is the same.

Vendors seem to use slightly different terminology for disks in the Sabre
series, which apparently has to do with the type of interface (SCSI, SMD,
or IPI) added to the drive.  For instance, one vendor offers the 9720-1230
with IPI interface as a CDC-97209-12G, where IPI is specified by the '9'
following "9720" (0=SMD,1=SCSI,9=IPI).  One vendor claimed the 4-digit CDC
designations are being changed to 5 digits because of the Seagate
acquisition.

Format.dat 1.26 of 89/09/06, from a 490, shows Sun support of the
following Imprimis drives on either the SMD-4 or ISP-80 (Sun IPI-2)
controllers:

disk_type = "CDC EMD 9720" \
	: ctlr = XD7053 \
	: ncyl = 1147 : acyl = 2 : pcyl = 1217 : nhead = 10 : nsect = 48 \
	: rpm = 3600 : bpt = 30240 : bps = 613
disk_type = "CDC 9720-850" \
	: ctlr = XD7053 \
	: ncyl = 1358 : acyl = 2 : pcyl = 1360 : nhead = 15 : nsect = 66 \
	: rpm = 3600 : bpt = 41088 : bps = 610
disk_type = "CDC IPI 9720" \
        : ctlr = "ISP-80" \
        : ncyl = 1631 : acyl = 1 : pcyl = 1633 : nhead = 15 : nsect = 82 \
        : rpm = 3600 : bpt = 50400 : skew = 0 : precomp = 0

The 3 disks shown above are, respectively, the Sabre 9720-368, 9720-850,
and 9720-1230.

Sun has tested the 2HP 1150 model internally, but apparently is not
offering them because they aren't currently available in quantity.  One
contact, a large/favored Sun customer, asked Sun for this drive but was
turned down; however, another contact indicated that his Sun salesman let
him order one of these.  Our Sun salesman had the following to say about
performance of the 2HP model:

|The work that we have done shows preliminary results that 
|sequential operations are about twice as fast with 6MB/s 
|drives versus 3 MB/s drives. Dual heads also seem to improve
|the random case by 20% to 30% since the lay out of the data 
|essentially doubles the logical track size. This automatically 
|forces a greater degree of sequentiality even in the random case.

Solbourne also has an IPI disk program.  The manager of their disk program
claimed that they would be offering IPI "within a few months", and had the
following to say about the 2HP drives:

|Yes, I'd agree with the statement that the position/placement of	
|data is transparent to the host.  It is all handled within the 
|drive and controller.

|Yes, we have two or three 2HP drives in-house now from Seagate.
|We are still tuning the IPI-controller/host interation so the 
|numbers we're seeing now are just preliminary.  We are confident
|we'll attain off each drive the physical data rate of 6 Mbyte/sec,
|a raw data rate of 4.5 Mbyte/sec and a file system data rate of 
|4 Mbyte/sec.  The steep fall-off in physical to raw data rates is
|due to the long data headers IPI defines for each 512 byte data 
|block.  I think it's on the order of 128 byte per block compared
|with 90 bytes per block under SMD.

The Imprimis sales literature for the 2HP confirms the nature of the
interface: "The splitting of the data on a write and the combination of
data on a read is done entirely by the disk drive interface and is
transparent to the disk controller and/or adapter."  That is, the drive
appears to the system to have half as many tracks per cylinder, with
tracks that are twice as long as for the single-head-transfer model.

As far as availability of the 2HP model, I didn't come across anyone who
actually had one at the time my request was written.  A number of vendors
claimed that they couldn't get them.  However, one contact said that
Peripheral Designs (see below) claims they can get them, for a price of
~$11500.  One other contact claimed that vendors have offered him the
97229, although he didn't say which vendors.  Since one contact claimed
that Sun had signed an exclusive deal with Imprimis, it may be that the
2HP drive is only available from sources who had contracts for it that
predate Sun's contract.

Several contacts have purchased the 9720-1230 drives from 3rd party
suppliers and formatted/run them without problems, so 3rd party sources
can save you quite a bit, esp. if you don't qualify for Sun's category B
discount.  Following are the 3rd party sources we've identified so far.
The lowest prices we've heard of for the 97209-1230 and 97229-1150 have
been ~$6800 and ~$11500, respectively.

Andataco 				800-334-9191
Aviv					617-933-1165
Consan; Eden Prairie, MN		612-949-0053
Cranel 					614-433-0045
Falcon Systems, Sacramento		916-344-1221
Microtek				?
National Peripherals			?
Peripheral Designs			404-263-0067
Peripheral Devices, Chicago		708-894-9050
R2D Distributing			303-799-9292
Rorke Data [wholesale only, I believe]	612-829-0988

CAVEAT: when you get that best price, make sure it includes the front
panel (controls), cables, and mounting hardware.  Some vendors don't seem
to have, or even be aware of, what kind of hardware is required to mount
these drives in the new Sun Data Center Server cabinet.  One vendor has
told us that the 19" rack hardware will work in the Server cabinet, but we
haven't been able to verify that.

As far as controllers, we have not considered using anything but Sun's
ISP-80, which was developed internally at Sun.  Those who don't use Sun
support may be interested to know that Xylogics will have their IPI-2
controller available for delivery from their distributors in early May, in
both single and dual channel models.  (The dual-channel model acts like
two controllers operating in parallel, saving you a slot.)  I don't know
who all their distributors are, but I believe Falcon is one.

Disclaimer: All of the above, or none of the above, may be true.

Ed Arnold * NCAR * POB 3000, Boulder, CO 80307-3000 * 303-497-1253(w)
era at ncar.ucar.edu [128.117.64.4] * era at ncario.bitnet * era at ncar.uucp
"Life is kind of like a B-grade movie; you don't want to cut it short,
but you don't want to roll it again, either."	--Ted Turner