Looking for a big Unix box

[Neil Gorsuch]

In article <18375 at eerie.acsu.Buffalo.EDU> pjg at autarch.acsu.buffalo.edu (Paul Graham) writes:
>In article <1990Feb25.075337.22513 at zardoz.cpd.com>,
>neil at uninet (Neil Gorsuch) writes:
>|In article <long-id at ucselx.sdsu.edu> nash at ucselx.sdsu.edu (Ron Nash) writes:
>|>We are looking for a Unix engine that will support at least 100
>|>concurrent users.  It would be nice if it could be expanded to support
>|Instead of buying a single BIG machine for a BIG price, look to where
>|the best deal is in (MIPS+Mbytes/$), which is currently desktop
>|workstations, and buy some of those, TO BE USED AS MULTI-USER
>|MACHINES.
>[ and proceeds to describe a cluster of workstations acting as a timesharer]
>last semester we went looking for a timeshare machine.  when we
>settled on a SPARC compatible system it was suggested that we consider
>purchasing a roomful of 4/60s rather than spend the money on a 4/490
>and a solbourne 5/802.  my answer then and even more so now is bzzzzt,
>wrong and no prize for you ;-).  i wouldn't think for a second of putting
>10 users on anything like a 4/60 let alone 20 (my workstation is a
>4/60, with 12MB and the fast disk).  i also think such a cluster would
>be nightmare to manage without having the users files on a server.

Methinks you don't know how to configure a Sparcstation for maximum
performance, or that you haven't tried one with > 16 Mbytes yet 8-).
A Sparcstation with 32 Mbytes or more of memory and a couple of 16 mS
disks is VERY snappy for 10 or so users (or use 11 mS disks if you
really want to be impressed.  And as for system administration, just
designate one of the machines as your main machine, and use rdist or
rcp or whatever for configuration files and local binaries.  Since you
essentially have clone machines except for user's files, it should be
easier to manage than 2 different types of machines (some programs
need to be re-compiled between the Solbourne and the Sun, and they
didn't do exactly the same things for systems directory trees).
Sprinkle the users's files appropriately, with NFS mounts everywhere
in case a user moves around, and use Yellow Pages to cut down on
confusion.  Backups are easy with a shared Exabyte drive.

Please note that I have a Solbourne and a Sparcstation in my office,
and I do admit that I use the Solbourne as my main machine.  But we're
talking about the best bank for buck for a time sharing machine.  As
for a 4/490, it's basically a somewhat faster Sparcstation with an
overpriced card cage.  But for multi-user systems, I would much rather
have 3 or 4 Sparcstations with 32 or even 64 Mbytes each than a 4/490
any day, and so would the users that you divvy up per $ spent, if they
could compare both systems.  The Solbournes do real well at MIPS/$,
but their memory is proprietary with no third party availability that
I know of, while the Sparcstations have dirt cheap memory available
elsewhere.  Of course at 27 MIPS/$7450 list for a Data General Aviion,
they come in even better.  I know of a University that has done some
investigating on this subject and found that they can't touch the
price/performance of desktop workstations as multi-user systems after
they add up all the costs of disks and memory and serial interfaces,
and have even gone so far as to REQUIRE all future multi-user systems
campus-wide to be DECstations, at least until some new workstation
models are out.  What you have done is choose a Solbourne (a very good
choice 8-) for part of your "system", but then gone and bought an
overpriced card cage that is expensive to add memory and disks to for
the second part.

>i've become a big fan of shared-memory multi-cpu boxes.  i think
>they're clearly the wave of future.   why even sun will have one
>someday.

I completely agree, but for $'s spent, you probably can't beat the
desktops, and remember we're talking about a wave of 27 MIPS desktops
coming out in the next quarter or so.  Not to mention the Taiwan Sparc
machines due out soon.

>impertinent details: our budget was $250k (we came pretty close) we
>bought a 4/490 and 5/802 each with 64MB and about 2G of disk.

Perhaps the problem last summer was getting past 16 Mbytes in a
Sparcstation cheaply, but consider these costs now, assuming that you
have 70 MIPS in your "system":

6 Sparcstations with 8 Mbytes Sun memory each      $54,000
6 X 16 Mbytes (4 Mbyte SIMMS)                      $24,000 (approx.)
6 X 4 Mbytes (1 Mbyte SIMMS)                        $2,500
6 X 1.3 Gbytes shoeboxes (2 660 Mbyte disks each)  $36,000
1 Exabyte and 1 1/4" tape drive			    $4,500
misc costs (software, etc.)                         $5,000

70 MIPS, 168 Mbytes, 7.9 Gbytes                   $126,000

And if I went ahead and spent a hair over $250,000, I would end up
with a "140 MIPS, 336 Mbytes, 15.8 Gbytes" system.  And if I was
really gutsy and used 10 Aviions instaed of Suns, for the same price,
I can bump it up to about 270 MIPS, and none of your 70 users is going
to complain about getting only 1/7th of a 27 MIPS machine 8-).  The
trick is in finding desktop workstations that can have a decent amount
of cheap memory and disks and MIPS.  Hopefully, a lot more desktop
workstations will have multiple CPU boards, and they will come out
better in the equations.  If I had my Solbourne list prices handy,
maybe a 2 processor series 5 would be better overall, but I doubt it
with the price of their memory.

>we don't use serial ports and we didn't have to pay for terminal servers
>or maintenance (someone else's budget).  we spent about the same

I assume that someone else is providing ethernet based terminal
servers.  The other side of this equation is that someone else spent a
fair amount for your serial ports, and that with 65 people banging
away through the ethernet, you waste a lot of ethernet bandwidth and
host CPU time with the TCP overhead.  Whereas if you split the system
into smaller chunks with a bunch of serial ports directly in each of
the Sparcstations you can optimally place the serial lines, you will
save a noticable amount of $'s, and the hosts will be saving a
noticable amount of CPU time.  Not to mention that the users won't
have to log in through an ethernet server and THEN rlogin into one of
the hosts.

>we don't like putting all our eggs in one basket.

But you put it in 2 baskets, where I am proposing putting it in 6
baskets, which is even more reliable.  I'm not saying your choice is
bad (I love Solbourne), but I am saying that if you look at things in
a different light, you perhaps could have spent about half of what you
spent.  Don't let a Sparcstation with too little memory (12 Mbytes is
barely past the Sunos/sparc performance knee) sour you on the
possibilities that a uniquely configured Sparcstation can offer 8-).
And don't get the idea that I am pushing Sparcstations, they just
happen to be a very cost effective solution right now, plus I know
that there will be very cheap double digit MIPS versions out from
Taiwan soon.

--
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