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From: truesdel@ics.uci.edu (Scott Truesdell)
Newsgroups: comp.sys.mac,comp.protocols.appletalk
Subject: Re: Increasing RAM on AppleShare Server
Keywords: RAM AppleShare
Message-ID: <1989Oct11.022443.25922@paris.ics.uci.edu>
Date: 11 Oct 89 02:24:43 GMT
References: <349@sdcc19.ucsd.EDU>
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Organization: UC Irvine Department of ICS
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cc: zz1he@sdcc19.ucsd.edu

zz1he@sdcc19.ucsd.EDU (Heather Ebey) writes:

>Does anyone know for sure if increasing RAM on a 1MB Plus running
>Apple's AppleShare File Server and Printer Server software will
>increase performance?  

Well, yes... it will help a little bit.


>Each server services six workstations and 
>and ImageWriter II.  All software is on the server and is shared
>and accessed simultaneously from six Mac Pluses.

Ugh!  You CAN run AppleShare like that, but that has got to be
incredibly agonizingly slow. Plain and simply, LocalTalk does not have
1/10 the bandwidth (well, 1/40 :^) ) to support that kind of operation.
It is intended for printer and file sharing.


>We are thinking of increasing the RAM to 2.5 Megs.

That's a good number, though the performance won't be as much as could
be gained by, say, just switching to an SE, let alone a II or SE/30.


>Does anyone else have a simular lab setup and have experience in
>performance issues?  

I once had to use a Plus as an emergency server while an SE was getting
repaired on one of my low-performance nets. The degradation was very
noticeable.


>Is there any software that can be run from a client that will
>evaluate performance?

Well, just using a stopwatch (yes, dear friends, LocalTalk is THAT
slow) can yield some good insight into system performance.

Heather, I guess you think I sound pretty negative. The extra memory
WILL help a little bit and it's a pretty cheap upgrade, but I doubt the
clients will be able to feel the difference. Truthfully, the only way
it is feasible to run applications off a server without (to most users)
agonizing delays, is to go EtherTalk all around. That's pretty
expensive.  Especially considering printing solutions.

Even for straight file service, the Mac Plus has the slowest SCSI port
in the whole Mac lineup. The SE has over double the throughput of the
Plus through the SCSI port, and the SE/30 and II series doubles that
again. Then one would want to hang the fastest HD possible on the
server.  And still these gains would be miniscule when bottlenecked
through the two LocalTalk/AppleShare killers: 1/4 megabit/second
throughput and no multitasking.

What I mean by no multitasking, is that the server performs all its
tasks sequentially, one at a time. It recieves a packet. Stops
everything.  digests the packet. Stops everything. Processes the
command. Stops everything.  Goes out to disk. Stops everything. Caches
the disk fetches (this is the one place where the added memory would
help). Stops everything. Dribbles the cached packets out the LocalTalk
line. Stops everything. Acertains correct transfer of packets. Then
finally gets around to requesting more data from the server disk.

How this translates into performance is: Not only is LocalTalk extremely
slow, but 2/3 to 1/3 the time, it's not even being used because it's
waiting for the Mac to assemble and digest more packets! I guess there's 
some good in that scheme: with that miniscule bandwidth, it's the only way
other devices would ever have a fighting chance of arbitrating some
bandwidth!

So. You have got what you have got, as far as networks go, and there 
is no chance of petitioning for faster servers, let alone EtherNet. 
What next? Here is a run down of possible alternatives, cheapest first:

1. Adding RAM to the servers is cheapest but the performance increase 
   will be negligible.
2. Adding 2MB of RAM to every client will allow them to run RAMdisk
   software, transfer programs down to RAMdisk, and run with very 
   acceptable performance LOCALLY.
3. Upgrading the servers to SE/30s or, better yet, old headless Mac IIs
   will upgrade the performance noticeably over solution #1, but running
   applications from the server will still be a study in frustration.
4. Adding small hard disks to each client workstation. This would 
   yield benefits similar to solution 2 using more comventional
   methods at a higher (twice) cost.
5. Ugrade to EtherNet all around. This would make running off the servers
   tolerable, even pleasant almost, but would cost a small fortune. 

  
I hope this helps a little.

  Scott Truesdell
  Information and Computer Science
  U. C. Irvine
  714/856-5697

P.S. Of the 200 Macs I have networked in our department, only 5 of them
have ethernet cards  :^(  and there are no AppleShare servers with 
Ethernet.  :^(   This is sad. But this will change as part of incremental 
upgrades I have scheduled through next year. At least they let me have
some kick-butt servers! :^)

--
Scott Truesdell