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Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!tci!darcy
From: darcy@tci.UUCP (Jeff d'Arcy)
Newsgroups: comp.sys.apple,comp.sys.apollo,comp.unix.aux,comp.unix.questions,comp.sys.mac,comp.sys.dec
Subject: Re: Academic workstations -- Followups to comp.unix.questions ONLY
Summary: diskless is not always painless
Keywords: latency
Message-ID: <258@tci.UUCP>
Date: 13 Jun 89 16:14:03 GMT
References: <2326@internal.Apple.COM> <32705@bu-cs.BU.EDU>
Reply-To: darcy@tci.UUCP (Jeff d'Arcy)
Followup-To: comp.sys.apple
Distribution: usa
Organization: Technology Concepts, Inc. Sudbury Mass.
Lines: 55

In article <32705@bu-cs.BU.EDU> bzs@bu-cs.BU.EDU (Barry Shein) writes:
>
>>This should give you better performance because local 
>>disks should be faster than networks, but it also adds to the cost and 
>>administration effort.
>>                                                Rick Daley
>>                                                rpd@Apple.COM
>
>Bad guess, go measure it, because servers almost always have faster
>disks, controllers and bigger disk buffers remote disks are usually
>faster than local disks (assuming a reasonable network loading which
>doesn't have to be zero.)

Certainly, servers (at least those configured by sane administrators)
are likely to have faster, bigger disks etc. than would be feasible
for individual workstations.  However, latency is likely to suffer due
to the overhead associated with protocol encapsulation etc. especially
in heterogeneous environments.  If the application is doing something
simple such as a huge block transfer the performance hit won't be that
bad, but more complex operations involving random disk accesses will
hurt.

>An ethernet can deliver data at almost 1MB per second, go look at the
>specs on your standard 27msec SCSI cheapo, 20KB/sec is not unusual for
>maximum disk transfer rate, about 1/40th the speed of an ethernet.

At risk of repeating myself, this observation only applies to the simple
case where transfer speed is the limiting factor.  Unfortunately, latency
is frequently more important and is the first thing shot to h*ll in a
network environment.

>[very good points about parallelism and network administration
> deleted to save network bandwidth]

>However, I will agree that blaming it on the diskless workstations is
>a wonderful alibi, the yokels believe you and rarely ask you to
>actually do your job and find out what's really causing the problem.

>It's the diskless workstations, it's the diskless workstations (we
>know those diskless workstation users will never buy the local disks
>you recommend so it's a safe bet to blame it on them.)

>[attempted disclaimers deleted]

>I am not saying there aren't cases where a diskful workstation is far
>better, I'm just saying most people don't know what they're talking
>about or have motives other than understanding the technology.

"...don't know what they're talking about..."?  Disagreement is not
a sure sign of one party's ignorance, Barry.  I'm not saying that
local disks are the one and only way to go, but they are superior for
a wide range of applications.  I make my living in this field and I
am probably not alone in being offended by your implication that those
who disagree with you on this point are either foolish, lazy or
dishonest.