Are fileservers a waste of money

[Carl Rigney]

In article <550 at trlamct.oz> you write:
>X-Sun-Spots-Digest: Volume 7, Issue 261, message 5 of 16
>
>We currently have network running SunOS 4.0 consisting of:
>
>fileserver	Sun3/260	16M memory	xylogics 451
>						1 x fujitsu eagle
>						1 x fujitsu swallow

If you can put faster disks on this, get Sun's new SMD-4 controller, which
is supposed to double disk throughput.  I don't think it will work with
Eagles, though.  Seriously think about getting Sun's Pegasus CPU upgrade
(the 68030 that was announced 4/13) - it has a reworked I/O cache.  It's
supposed to significantly improve I/O, as well as giving you 7 MIPS
instead of 3.

>With the following diskless clients.
>
>1 x client	Sun3/60		12M memory	(lisp programming)
>3 x clients	Sun3/50		4M memory	(lisp programming)
>2 x clients	Sun3/50		4M memory	(C & fortran)

4 MB for SunOS 4.0 and Lisp is intensely masochistic.  Are your kernals
configured as small as possible?  Someone just posted an article to
Sun-Spots that says a diskful 4MB machine runs SLOWER than a diskless 4
MB, and a diskless 8MB machine runs twice as fast as either.  That might
mean you have to go 3rd party for the 3/50 memory, though.  If you have
the money you might see about replacing them with 8 MB 3/80's (a 68030
with cheaper memory), or even 16 MB.  Another possibility you might
investigate is getting one of CDC's new Wren Runner SCSI drives - these
have 10.5ms access time compared to the 20-30 MB for Sun's dogs.  They're
also synchronous, which only helps if you have a 3/80 or 4/60; the older
suns only support asynch SCSI (boo).

But more memory is better than more disk, generally.

>The problem is getting access to swap space on the disk.

Have you split the /export/swap across both disks on your server?

Also, have you looked at your ethernet to see what's going on?  How much
load does traffic show?  Would segmenting your net cut down, or are your
machines all that's on your wire?

>The alternatives appear to be :
>
>1. New high speed disk for existing server.

A waste unless you get the better controller, I suspect.

>2. New more powerful fileserver with high speed disk.

Upgrading the 3/260 (or just buying a 3/470 or 480) should be OK.
Upgrading is cheaper, probably, but Sun's being very aggresive about
Pegasus pricing.

>3. Providing 3/60s or equivalent with 20 Megs for the lisp programmers
>   and upgrading the 3/50s.

16MB 3/80s might be good.  Beware that that's all the memory they can
have, though.  If you have the money and your lisp works on the SPARC
architecture you might consider a 16MB 4/60 - 12 MIPS for the price of a
3/60, with synchronous SCSI!  Putting a Wren runner on one of those ought
to be a good time!  Of course, SPARC binaries are larger than 680x0, so
you'll need that extra memory...

>4. Providing local SCSI disks giving each client local swap space
>   (dataless client configuration)

This is the least effective answer, probably.  Especially if you buy your
disks from Sun.

>I personally feel that a more powerful fileserver is still going to suffer
>a bottleneck at the disk with clients fighting for access to swap space,
>even if a new server provided twice the disk I/O speed compared to the
>existing server.

You want two fast disks so you can spread the load among them, or better
yet two controllers.  First put as much memory as possible in your
workstations, then buy a 3/480-32 with 2 SMD-4 controllers and 4 892-MB
SMD Disks, or upgrade your existing 3/260 to as close to that as you can
afford.  For the fullblown system you're probably looking at ~ $100k
before discount, but your friendly Sun sales rep would know better than I.
And get Perfect Byte (or *someone*'s!) 2.3GB 8mm Tape drive for backups.

Caveat!  Your mileage could differ with the 3/480, 4/60, and 3/80 - after
intense study we're getting the first two, but I haven't had hands-on
experience yet.

I'll be interested to hear what everyone else has to say.

	--Carl Rigney
	cdr at amdcad.AMD.COM
	{ames decwrl gatech pyramid sun uunet}!amdcad!cdr
	408-749-2453

The Network is the network.
The Computer is the computer.
Sorry about the confusion.