Mini & Mainframe Power Requirements

From: Peter Prymmer <>
Date: Sun Jan 18 20:05:44 1998
Subj: Re: Mini & Mainframe Power Requirements

William Donzelli wrote:

>OK, running a big mini or a mainframe class machine is not for everyone.
>However, running a processor plus a single disk and perhaps a tape may not
>be all that bad. Water cooled machines, however, would be too much to
>For those that only want to plug things into the wall, turn back now!
>A typical mainframe machine from the past is going to want 3-phase power.

<more scary power specs snipped>

Well not necessarily. Of late IBM has been putting effort into making
S/390 (note: less than 7 years old and not quite a classic) available
to small shops: via the P/390 (a 7490 mainframe on a chip hosted by a pentium
running OS/2) and the R/390 (also a 7490 with an AIX host - RS/6k or PPC).
I must apologize: in a previous message I had referred to the mainframe on
a chip as a "3490" which is a tape drive not a CPU model number.

To the extent that S/390 derives its heritage from S/370 and S/360 such a
box may serve the needs of the mainframe hacker with a small power
capacity/budget. IBM's amazing efforts at preservation of backward
compatability are a big plus here: to a first approximation S/390 simply
adds features to S/370 (the parallel sysplex clustering ability allegedly
being quite highly advanced nowadays e.g.). Unfortunately the purchase
price won't help the budget minded hacker: a new P/390 runs $50k to $100k and
the R/390 a bit more.

I've used a P/390 and must say that it is quite a machine: all DASD
communication channels are actually handled via a software emulation that
runs under the host OS/2 machine, but other than that it seems much like a
mainframe. You can run with RAID 0,1,3,5 using PC type drives.
The 7490 can run OS/390 (the new name for MVS), VM/ESA, as well as VSE/ESA
(the new name for DOS since about 1987).

Interestingly enough IBM recently upgraded their P/390 production line
to move from 90 MhZ Pentiums to 200 MhZ Pentiums and touted that customers
could expect throughput rates to increase a whopping 10% (this gives you an
inkling of how much the host OS adds in overhead). According to an IBM
technical contact there are shops that are actually running P/390s in a
production environment: doing payroll, accounting and whatnot. This
despite the fact that the intended market was primarily for software shops
porting code to S/390.

Perhaps the most unusual thing about S/390 are the OpenEdition environments
that run under the various OSes. They give you unix on the mainframe and the
OpenEdition environment under OS/390 is now known as "UNIX System Services for
OS/390". The irony being that MVS is actually 3-4 years younger than UNIX:
UNIX started in 1969, MVS was announced in 1973 and shipped in 1974.

At any rate keep an eye out for P/390 on a PC Server 500 (maybe the P90s will
wind up on the used market?) and the equivalent R/390 machine - they take only
wall plug 110 AC and will let you hack JCL, assembler, and CLISTs to your
heart's content - destined to be classics.

Peter Prymmer
Received on Sun Jan 18 1998 - 20:05:44 GMT

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