SUMMARY client/server ratio continued

From: Daryl Crandall (daryl@dash.mitre.org)
Date: Thu Jul 19 1990 - 11:53:58 CDT


My original summary seems to have been truncated. Here is the continuation.

        Daryl Crandall
        daryl@mitre.org

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Well, inasmuch as our measurements have shown that one 4/60 can blast at
least one network to oblivion, it's my considered opinion that a
diskless sun 4 is penny wise and pound foolish. We're using 4/60's and
4/60c's to do swap and file service for 3/50's, and they handle 15
clients just fine.

But you haven't said very much about your 4/390, so I don't know very
much. What is the mix of clients? What do they do? How much memory?
What kind of disks on the server? What, if anything, do people do on
it? I can well believe that 20 fast clients bogs down even a 4/390 (it
might not bog down a 4/490, but it might bog down the ethernet).

Sun recommends not more than 15 clients or so per server. That seems
about right, based on our experience here. On the other hand, we have a
few diskless 4/60's (really just for ha-ha's, not because we take them
seriously). They really do hit their servers, and they run very slowly
to boot. Remember, that machine has 6~8 times the CPU of a 3/50 (12.5
mips vs. 1.5~2), a very fast memory bus (in all our measurements a 4/60
is faster than a 4/280), real I/O capability, basically a very real
machine. Not a toy like the run of the mill 3/50. We're using them as
servers, and even with SCSI's they blow the doors off the 4/280's with
SMD's of various kinds.

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We sell a tool called EtherView which includes a tool to measure NFS load
(calls/sec) and performance (average response time for each call) over
an extended period of time (such as a working day).

This tool will let you look at your load and performance as a function of
time interval, server, client and NFS proc. You could use this tool to see
how the load varies during a day and what happens to the response time.
If your average response time gets significantly worse during the day as load
increases then your server might be overloaded. In addition, it will let
you see how the server load is apportioned between various clients etc.



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