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Subject: Re: Mailing list hardware question
From: "Jonathan M. Bresler" <jmb @ FRB . GOV>
Date: Thu, 30 May 1996 09:30:58 -0400
To: Mark J Bradakis <mjb @ spitfire . cs . utah . edu>
Cc: list-managers @ GreatCircle . COM
In-reply-to: Your message of "Wed, 29 May 1996 18:28:58 EDT."

>I know this could easily get out of hand, but I'm wondering about changing
>a mailing list server.  Currently, it is an HP/715 with 32 megs of RAM,
>a SPECint92 rating of 36, SPECfp of 72.

	SPEC*92 has been repudiated by SPEC.  its a computational 
benchmark of fixed size.  it fits in L2 cache.  Parts have been cooked.
Mail is a network app.  you need a host that has good networking and 
fast disk.

>It serves a couple of dozen automotive related lists, under majordomo,
>with a "fanout" of about 2.5 million messages per month, where fanout is a
>somewhat useless number found by multiplying the number of list members by
>the number of messages.

	i am using majordomo for the FreeBSD mailing lists.  we have 11,000
direct subscribers, some number of which are mail exploders.  since may 25th
4am (as i write its now may 30th 6am) we have handled 890,000 messages 
and 1.75GB of mail thru the smtp8 mailer alone.

>That is, if there are 500 members, and 1,000 messages per month, that's a
>fanout of 500,000 per month.  Better metrics for mailing list loads would
>also be welcome.

	we use a PC with 64MB, 4 scsi disks.
	
>So I'm currently wondering if some Pentium based PC, with a decent ethernet
>card, can handle the load.  The machine also serves as an FTP site, with a
>dozen or so connections during the day, and as a web server.  The CPU is
>usually about 90% idle, while it waits for disk IO and 30 to 40 packets
>per second to get pumped out to a fairly busy net.  Could a new Pentium,
>running Linux, perhaps, handle this sort of work?

	ftp, web, mail.  there are all net and disk intensive programs.
a *good* quality 586 will do fine.  i would recommend against linux.
its networking and *synchronous* disk speed are not as fast as FreeBSD.
read the usenix96 paper by mary baker and kevin lai of stanford
http://plastique.stanford.edu/~mgbaker/publications/usenix96.bench.ps
context switching will be critical as well.

short summary:
	context switch:  FreeBSD flat graph @ 100usec
			 Linux exponential graph crosses FreeBSD at 19 procs
	network tcp:	 FreeBSD: 65.95MB/s
			 Linux:   25.03MB/s
	disk synchronus: FreeBSD: 65ms
			 Linux:   no data available
			 Linux: (asynchronous) 0ms

			 0ms means that the data is *not* on the disk.
			 should something bad happen the data is gone.
			 ouch.

jmb

-- 
Jonathan M. Bresler             202-452-2831                 breslerj @
 frb .
 gov
MS-169          Federal Reserve Board of Governors        Washington DC 20551
Speaking for myself.  Others speak for the Federal Reserve Board of Governors




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