sbw@naucse.UUCP (Steve Wampler) (01/28/89)
We are considering buying some DECstation 3100's for use in
a network. Although essentially diskless, I like the idea
of having a small 'paging' disk in each. Dec sells a
104MB 3.5in disk for just this purpose. I was wondering
what other options might be (and for how much). The
controller is SCSI, so I assume that most SCSI drives
would work, but I know *nothing* about 3.5in SCSI drives.
I know CDC makes a 16.5ms 100MB 3.5in drive, for example,
but haven't heard of a SCSI version of it.
If you know of any that are reasonable (and I assume that,
for paging, speed is pretty important), please email me.
By the way, I have one piece of paper from DEC telling me
the 3100 enclosure can take two 1/2ht 3.5in drives, but
all the other pieces of paper only mention putting one
such beast internally. Anyone know for certain?
Thanks!
--
Steve Wampler
{....!arizona!naucse!sbw}rsp@decvax.dec.com (Ricky Palmer - (603)881-0370 - ZK3-3/T74) (01/29/89)
------- Check with your sales rep to be sure, but I believe you can put two 3 1/2 inch drives (RZ23's) in the 3100. --- Ricky Palmer Ultrix Advanced Development --- Digital Equipment Corporation --- Nashua, New Hampshire --- ... One of the fathers of PMAX ...
vixie@decwrl.dec.com (Paul A Vixie) (01/29/89)
[Steve Wampler] # We are considering buying some DECstation 3100's for use in # a network. Although essentially diskless, I like the idea # of having a small 'paging' disk in each. Excellent idea. Never has a workstation needed local (i.e., fast) paging as much as this one -- you've got more horsepower than an 8800 and slightly larger executables, so you end up with this burning itch to run 35 things on the machine all at the same time just to see it go slow. 24MB isn't enough memory to hold everything it takes to make the CPU actually bog down. Therefore you do a little paging now and then, and if you're waiting for NFS to give you the data (DEC doesn't use ND, never has, never will), you'll be very sad and somewhat frustrated. # Dec sells a 104MB 3.5in disk for just this purpose. I was wondering # what other options might be (and for how much). The controller is SCSI, # so I assume that most SCSI drives would work, but I know *nothing* about # 3.5in SCSI drives. "Most" is the key word, and it's wrong. The proper word is "some". SCSI is not a perfect standard and there are many imperfect implementations of it. I understand that we (DEC) had to test several SCSI drives before we found one that worked "properly", whatever that means. # I know CDC makes a 16.5ms 100MB 3.5in drive, for example, # but haven't heard of a SCSI version of it. I have not heard of a NON-scsi version of it. Those are great drives; I'll bet they work "properly", whatever that means. I've also heard some good things about Fujitsu 3-inchers. # If you know of any that are reasonable (and I assume that, # for paging, speed is pretty important), please email me. The SCSI interface will push synchronous SCSI data down the wire at 4 MB/sec, so make sure your drive has fast sychronous support. Some drives either don't have synchronous mode or have it but run about 1 MB/sec. # By the way, I have one piece of paper from DEC telling me # the 3100 enclosure can take two 1/2ht 3.5in drives, but # all the other pieces of paper only mention putting one # such beast internally. Anyone know for certain? There's room in the box for 2 half-height 3.5-inch drives, but the power supply may or may not have the juice to run two of them if they're hungry and you've got a full 24MB. Check, as Ricky Palmer suggests, with your salescritter; don't be surprised if they say "only one drive is supported", but get your techies to look at the power supply with a watt-meter and at the specs for power-supply and your proposed extra drive; you may end up (no promises and please don't quote me) voiding your warrantee and/or service contract, but there may be enough power in there to do everything. Disclaimer: it's 1:30 in the morning, and I'm sure my manager doesn't know where I am or what I'm doing; I'm sure he will disavow all knowledge of my activities if you call him. -- Paul Vixie Work: vixie@decwrl.dec.com decwrl!vixie +1 415 853 6600 Play: paul@vixie.sf.ca.us vixie!paul +1 415 864 7013
pavlov@hscfvax.harvard.edu (G.Pavlov) (01/30/89)
In article <1143@naucse.UUCP>, sbw@naucse.UUCP (Steve Wampler) writes: > We are considering buying some DECstation 3100's for use in > a network. Although essentially diskless, I like the idea > of having a small 'paging' disk in each. Dec sells a > 104MB 3.5in disk for just this purpose. I was wondering > what other options might be (and for how much). The > controller is SCSI, so I assume that most SCSI drives > would work, but I know *nothing* about 3.5in SCSI drives. > It would be nice if people reported experiences with 3rd party equipment on these workstations after they have failed or succeeded in adding them in. DEC has put together a highly competitive offering here, and I assume that there will be a lot of interest in it in new quarters. We have a MIPS machine with the same processor the the DECstation uses and it is quite a performer - runs circles around the SUN 4/260 for a lot less money. To address the above question specifically, tho, it is my understanding that DEC is OEMing the three drives it "released" with the new workstations. Does anyone know the manufacturers and model nos. ? Seems that this would be the safest way to proceed... greg pavlov, fstrf, amherst, ny
rogerk@mips.COM (Roger B.A. Klorese) (01/31/89)
In article <4320@decvax.dec.com> rsp@decvax.dec.com (Ricky Palmer - (603)881-0370 - ZK3-3/T74) writes: >--- Ricky Palmer Ultrix Advanced Development >--- ... One of the fathers of PMAX ... I feel like a maiden aunt, then... ;-) -- Roger B.A. Klorese MIPS Computer Systems, Inc. {ames,decwrl,pyramid}!mips!rogerk 928 E. Arques Ave. Sunnyvale, CA 94086 rogerk@servitude.mips.COM (rogerk%mips.COM@ames.arc.nasa.gov) +1 408 991-7802 "It's not the length, it's the depth" -- Howard Solomon
rsp@decvax.dec.com (Ricky Palmer - (603)881-0370 - ZK3-3/T74) (02/03/89)
-------
(By the way, hi, maiden Aunt Roger....-rsp)
There have been several inquiries about SCSI and the
DECstation 3100 (PMAX). The usual caveat applies, i.e., only DEC
supplied SCSI devices are ever supported or recommended by DEC;
however, the SCSI bus on the 3100 is ANSI standard. The Ultrix SCSI
driver currently supports only disk and tape (random access and
sequential access) SCSI device types, but it will eventually be quite
easy to add other kinds of SCSI devices. The devices must adhere to
the electrical specifications defined in the ANSI specification and
should also support the "common command set" as defined in that
document. As Jim Gettys has pointed out you are always on your own and
some non-DEC disks/tapes may very well have microcode or design
differences that preclude their use on the DECstation 3100. Our own
experiences in testing new devices uncovered microcode bugs in several
devices we qualified.
The bus is single-ended and cannot exceed 6 meters in length.
And 6 meters means exactly 6 meters. This includes any cable inside
the box plus however much cable is used outside the box. The bus is
very sensitive to this length and many problems that wouldn't exist
otherwise may crop up if this rule is not followed closely. The 3100
supports both synchronous and asynchronous devices. The bus data rate
for synchronous transfers is 4 MB/sec. The SCSI host adapter is a
custom DEC gate array and as such is proprietary. You should consult
the appropriate person for information on what configurations of
disks/tapes are available and recommended by DEC. One recommended
SCSI ID ordering is given below but may differ depending on your
particular configuration:
7 - reserved
6 - host DECstation 3100 CPU (the boot ROM sets it to 6)
5 - TK50Z TAPE asynch. device only (external sidecar)
4 - RRD40 CDROM asynch. device only (external sidecar)
3 - RZ23 DISK asynch. device only (internal mount only)
2 - RZ23 DISK asynch. device only (internal mount only)
1 - RZ55 DISK synch. device (can run asynch. too)(external)
0 - RZ55 DISK synch. device (can run asynch. too)(external)
This list is only valid for this particular combination of
devices. Obviously if you decide to put together a 3100 with only
external RZ55's you could conceivably have a synchronous RZ55 at ID
slots 0, 1, 2, and 3 and no RZ23's. The above example has the
recommended ID values for the particular devices used but is by no
means all inclusive. The logic above is simply that the slower devices
(tape and CDROM) should be closest to the CPU and the fastest devices
farthest away from the CPU. There is no requirement as to how many
synchronous versus asynchronous devices you can have. If you wish to
have all synchronous it will work or all asynchronous will work. The
most important criteria for performance of a given SCSI target is how
well the target is built. Some of the latest SCSI devices I have seen
are quite nice.
For those who would like to connect their own devices to the
bus the Ultrix driver allows the addition and definition of new
devices in the "scsi_data.c" file supplied with every binary or
source license, in other words, you don't need anything but your
friendly editor and some information on your particular device to add
it to the data file, recompile the data file, and reload your kernel.
An example disk entry might look like the following (this assumes
an entry for the partition table for your device not shown here):
#define DEV_MYDISK "MYD100"
struct scsi_devtab scsi_devtab[] = {
{"MYDISK 100", 10, DEV_MYDISK, SZ_DISK, sz_myd100_sizes, SCSI_TRYSYNC | \
SCSI_STARTUNIT | SCSI_REQSNS | SCSI_TESTUNITREADY | SCSI_READCAPACITY, 0 },
{ 0 },
};
where the first field is the vendor returned string
identifying the drive, the second field is the length of the string,
the third field is the Ultrix name for the device, the fourth field is
the class of SCSI device, in this case disk, the fifth is the
partition table entry, and the last field is a mask of bits that
defines what action(s) the driver probe routines should take upon
system boot. All the currently defined fields are:
SCSI_TRYSYNC - set the device up as synchronous
SCSI_REQSNS - send a REQUEST SENSE SCSI command
SCSI_STARTUNIT - send a START/STOP UNIT SCSI command
SCSI_TESTUNITREADY - send a TEST UNIT READY SCSI command
SCSI_READCAPACITY - send a READ CAPACITY SCSI command
SCSI_NODIAG - don't issue SEND DIAGNOSTIC command
A sample tape entry along with the disk might be:
#define DEV_MYTAPE "MYT100"
struct scsi_devtab scsi_devtab[] = {
{"MYDISK 100", 10, DEV_MYDISK, SZ_DISK, sz_myd100_sizes, SCSI_TRYSYNC | \
SCSI_STARTUNIT | SCSI_REQSNS | SCSI_TESTUNITREADY | SCSI_READCAPACITY, 0 },
{"MYTAPE 100", 10, DEV_MYTAPE, SZ_TAPE, sz_null, SCSI_NODIAG, 0},
{ 0 },
};
The data file that comes with Ultrix has a default case for
any disk you happen to try. If it works for a particular disk you
have only a 'c' partition initially, but the partition table can be
changed once your up and running off your system disk. This is more
of a "last resort" attempt to size any random disk that you might try.
I hope this answers some of the questions out there. This interface is
not laid in stone and could change in future releases as new revisions
and changes to the driver occur, but for the initial cut at it with
what devices we did support it took us a long way toward supporting
disks and tapes easily and effectively. And boy does this little box
push the data around fast!!!!
--- Ricky Palmer Ultrix Advanced Development
--- Digital Equipment Corporation
--- Nashua, New Hampshire
--- ... One of the fathers of PMAX ...