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Date:      Wed, 6 Mar 1996 20:45:28 -0700 (MST)
From:      Dave Andersen <angio@aros.net>
To:        jgreco@solaria.sol.net (Joe Greco)
Cc:        mtaylor@cybernet.com, hackers@freebsd.org
Subject:   Re: Proper FreeBSD news machine
Message-ID:  <199603070345.UAA21122@terra.aros.net>
In-Reply-To: <199603062336.RAA04112@solaria.sol.net> from "Joe Greco" at Mar 6, 96 05:36:42 pm

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Lo and behold, Joe Greco once said:

For comparison:

> Let me sketch out my news operation here.  I have multiple news peers, very
> few readers, I retain about a million articles (5 to 7 days retention)..

  We have 6 peers, and about the same amount of retention.

> good deal, not because CPU was much of an issue.  I'd say I was running
> 30-40% idle.  That suggests a DX2/66 would be squeaky, though.  The box is
> now a P90 and I notice a slight performance improvement.

   We're running on a P100 and typically have 90% idle, except during the 
news.daily run (which admittedly takes about 7 hours or more).

> > B) how much RAM?  32 Mb enough?
> 
> Memory: 16MB + sizeof(history.pag) * 2MB + numclients * 1MB + numfeeds * 1MB.
> 
> "clients" are expected simultaneous nnrp's.  feeds are outbound feeds,
> innxmit or nntplink, no matter.  sizeof(history.pag) in megabytes.

   It almost sounds like you developed this forumla before the 
sharedactive patch meandered its way around.  I'd have agreed with you 
before (it would say we needed about 56 megs of ram, and we were actually 
using about 49 during non-expire times), but the sharedactive patch 
reduces the memory usage from 1.3M to .3M per client (roughly) on our 
system.  Obviously, the larger your active file, the more benefit you'll 
achieve from this.  On a 64MB machine, we run with about 28 megs used for 
cache on average.  This is with between 5 and 20 clients.

> it will begin to fight for pages with INN, and both your innd and expire
> processes will slow to a crawl.  You also must factor in memory for other
> running processes (i.e. clients and feeds), and the OS itself needs some RAM
> (16MB, let's say, for kernel, cache, scratch, etc).

   Quite fair.  I think you can squeak by on a bit less than this if 
you're .. ahh, willing to put up with some burps and slowness, but given 
that this machine is also going to act as a router -- I agree completely.

> > C) would separate SCSI busses help?  (I plan to put a second 4.3Gb HD
> >    in for the rest of the news spool)
> 
> Go PCI SCSI if you can.  Also, the more disks, the merrier (I have 14 but
> then I'm a performance freak).

  As a side note, be sure to keep the history* files on a separate spool 
from the rest of the world.  Do the same with the overfiew files if you 
keep them.  It'll make your life a lot happier.

> > D) whose SCSI card has the 'best' performance?
> 
> I've had good luck with the AHA3940 and NCR-810 based cards.  The AHA2940
> should work well too.

   It's a good performer, though we have occasional stability problems 
with it.  I think it's more due to one of the drives -- a 9gb micropolis 
for storing alt.binaries -- than anything else.

> Pay close attention to the memory advice.  I see so many people try to get
> by without enough memory.  It doesn't pay.  I run Exec-PC's news operation
> and they try to squeeze 150-200 nnrp clients onto a box with 128MB RAM.
> They complain to me that it "takes forever to connect".  I wonder why.  ;-)

   That's masochism for you. :-)

   -Dave Andersen

-- 
angio@aros.net                Complete virtual hosting and business-oriented
system administration         Internet services.  (WWW, FTP, email)
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  "There are only two industries that refer to thier customers as 'users'."




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