Path: utzoo!attcan!uunet!cs.utexas.edu!mailrus!cornell!uw-beaver!rice!brazos.rice.EDU!evan
From: evan@brazos.rice.EDU (Evan Wetstone)
Newsgroups: comp.protocols.appletalk
Subject: Re: LocalTalk Speeds
Message-ID: <1736@brazos.Rice.edu>
Date: 28 Sep 89 01:47:18 GMT
Sender: root@rice.edu
Reply-To: evan@rice.edu
Organization: Rice University, Houston TX
Lines: 59


In article <2476@dogie.macc.wisc.edu>, yahnke@vms.macc.wisc.edu (Ross
Yahnke, MACC) writes:
> I'm looking for advice in setting up a mac network for a student
> lab. We'll need about 60 Macs to serve all the students. They
> will be running MacPascal and some Fortran program almost
> exclusively. I hope to have them using LaserWriters.
> 
> I know that LocalTalk, (and especially PhoneNET) is much cheaper
> than Ethernet. I'm wondering if it would pay to use Ethernet, tho.
> 
> Let's say we have 15 Mac SEs hooked up to one Mac SE/30 as server,
> using PhoneNET and AppleShare. The Mac SEs *will not* have hard
> disks; this will prevent virus transmission and make the macs
> unappealling to non lab users to use, (it's an open access lab,
> anybody could walk thru and we have problems now with non lab
> people using the current mac pluses w/hard disks. Too many
> viruses and too many purloined copies of MS-Word floating about).

This sounds amazingly similar to what we have done at Rice.  
Here's our setup:
We have about 50 Mac II's with 2 floppies each (no hard disks 
for the same reasons you mention above) all hooked together using
LocalTalk.  This is hooked up to a Kinetics KFPS-2 running KIP.
We run the CAP aufs code to run a public AppleShare off of a Sun 3.

> So lab users will have to boot off of floppies, no big deal.
> We repeat this setup 4 times and therefore have 60 macs w/four
> servers. Would 15 nodes trying to run an application like
> MacPascal hopelessly bog down the SE/30? Would spending $600
> extra for an Ethernet card make things more responsive?

Here's what we discovered:
Performance was bad.  Real Bad.  It appears that the major bottleneck
is LocalTalk, which runs at 230Kbs.  We are purchasing EtherTalk cards
for all of the Mac II's to eliminate this bottleneck.  We are also 
purchasing some Mac II's with hard drives to act as file servers so 
we can stop using aufs.  Hopefully we will see some improvements.
I firmly believe that 15 nodes trying to launch MacPascal off
of a single SE/30 will force the SE/30 to its knees and possibly all
the way to a meltdown........;-)

> After looking at the May 89 issue of MacUser that discusses
> this my genereal impression is that Ethernet wouldn't help
> that much, but the fast SE/30 would. Using DaynaTALK would
> help even more and still be cheaper than Ethernet.
> 
> My main concern is that the net not become totally unusable
> when it is being fully utilized, which will happen a lot.
> Any comments are much appreciated.

Using the setup you describe above, I think that during peak
usage, the network will grind to a halt.  Anyway, I would be
interested in hearing what you finally decide to do.

----
Evan R. Wetstone			Internet:  evan@rice.edu 
Network and Systems Support		  BITNET:  evan@ricevm1
Rice University, Houston TX