gauging interest in VAX 6000-530

From: Chris Kennedy <chris_at_mainecoon.com>
Date: Sun Oct 24 22:33:47 1999

Mike Cheponis wrote:

[stuff deleted]

> The paradigm today is client on Ethernet, server cluster in the back room.
> Scalable, cheap, reliable.
>
> One Big Box In The Back Room is what people did in the 40s, 50s and 60s.....

And 90s. Data is expensive to ship and dramatically more expensive to keep
coherent when distributed, even across short distances and gigabit networks.
If this were not the case we wouldn't see Enterprise class machines being
pushed out the door, and I wouldn't be watching a client who accepted the
notion of "cheap" computing clusters without stopping to think throw more
and more hardware at their back-end -- what was originally a single US170E
became a 2300, then a 2400, then a pair of 2400s and now a four-processor
E450 and a 2400 -- all to support a handful of 500MHz NT clients who are
doing all the computations. That right, no integer math, no floating point,
not nuthin' on the backend except moving data around.

Draw a typical "modern" distributed computing architecture on the wall,
then do the same for a 360 TSO system using 3270s. Damn if the pictures
don't look the same save for the labels on the boxes. The 3270 has been
replaced by a thin client, and the Big Blue box has been replaced by a
big-ass Enterprise 10K from Sun. Yeah, the communications links are
faster, but with more processing done on the front end I generally have
to ship more data more often and go through parlor tricks to keep the
stuff in synch -- not an issue for passive web browsers, but then the
browser is a lousy model for many applications.

The bottom line here is the speed of light; at some point I need to do
more things in parallel to increase my throughput. A typical PC with a
single bus simply can't push as much data as a large machine with a bunch
of independent dedicated buses managed by their own controllers.

Of course, none of this has anything to do with the 486 integer ALU vs.
a Vax 8mumble ALU -- it has to do with the overall architecture of
the machine. Given a similar bus and channel controller structure
one could get the same throughput out of an x86 as a Vax, MV or
309x class machine.

> >>Hey, I'm not saying the original IBM PC was going to outperform the VAX 6500;
> >>but a modern PC will crush any VAX in any application, IMHO, with equivalent
> >>h/w attached.

The problem is that I can't attach equivalent hardware. Given the choice between
deploying Solaris on an x86 or a sparc I'll take the x86 90+% of the time
-- on the desktop the price-performance is tough to beat. However, there's
simply no way that I can do it for anything that requires shuffling around
large amounts of data. I can't get a PC that has enough aggregate bandwidth;
an Enterprise machine will smoke the PC's doors off despite the fact that the
PC is clocking hundreds of Mhz faster (aside: does anyone know offhand what
the typical CPI is for the Ppro, PII and PIII?). Again, that's not a commentary
on the processor, it's a commentary on the overall architecture. A Sequent, for
example, has a far better architecture than any PC I can buy.

> >
> > Speed isn't everything.
>
> You're right, speed isn't everything; it's the -only- thing! ;-)

That's correct. Unfortunatly, CPU speed is kinda meaningless in and of itself,
save for some very degenerate applications (i.e., no I/O, no external
memory references, everything resolves in on-board cache, etc.)

> > I'd rather have a nice VAX than a modern PC,
> > you've also got to consider the fact that PC's aren't the most reliable of
> > platforms, and most run an OS that totally sucks!
>
> My PCs are damn reliable; are you buying junk? They are -waaaaaaaaaaay- more
> reliable than the VAX-11/780s, VAX-11/750s and VAX-11/785s that I have
> used in the past. (I run BSDI unix on a Pentium Pro, as well as NetBSD on
> other machines, and they have -never- crashed.)

I run Solaris on Ppros, PIIs and Sparcs, Linux on PIIIs and OpenBSD on Sparcs.
The PCs are less reliable than the sparcs, but even then they're far more
reliable than anything from the late 70's. If we look at contemporaries, my
fuzzy recollection is that the 785 I was using was generally a hell of a lot
more reliable than the PC/AT I was using at the time -- and the 785 cranked
a hell of a lot harder than the AT did.

Cheers,
Chris
-- 
Chris Kennedy
chris_at_mainecoon.com
http://www.mainecoon.com
PGP fingerprint: 4E99 10B6 7253 B048 6685  6CBC 55E1 20A3 108D AB97
Received on Sun Oct 24 1999 - 22:33:47 BST

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