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Date:      Tue, 20 Mar 2001 09:27:17 -0800
From:      Alfred Perlstein <bright@wintelcom.net>
To:        "Michael C . Wu" <keichii@iteration.net>
Cc:        dillon@FreeBSD.ORG, grog@FreeBSD.ORG, fs@FreeBSD.ORG, hackers@FreeBSD.ORG
Subject:   Re: tuning a VERY heavily (30.0) loaded server
Message-ID:  <20010320092717.R29888@fw.wintelcom.net>
In-Reply-To: <20010320111144.A51924@peorth.iteration.net>; from keichii@iteration.net on Tue, Mar 20, 2001 at 11:11:44AM -0600
References:  <20010320111144.A51924@peorth.iteration.net>

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* Michael C . Wu <keichii@iteration.net> [010320 09:11] wrote:
> [Lengthy email, bear with me please, it is quite interesting.
> This box averages 30.0 load with no problems.]

cool..

> system stats at 
> http://zoo.ee.ntu.edu.tw/~keichii/

Where's the crashdump/traceback?

> Physical memory is 2.5 GB.  We do MFS and it croaks/crashes
> at midnight, our peak load time.  We do md0, it croaks before
> peak time.

Explain the crash.  What is md0/MFS being used for?  Why do you
need it?

> Due to the structure of BBS's, we cannot split the load across
> different servers.  We also think that we probably cannot
> get more performance out of hardware upgrades that we can afford.
> (i.e. Please don't tell us to buy a Starfire 4500 :-) We are all volunteer
> werkers at El Cheapo university budgets.)

Well, getting hardware RAID is always a nice thing and really not
too expensive.

> We have followed Alfred's advice to do sysctl -w vfs.vmioenable=1
> It allows us to survive the peak load a little longer than before.

cool..

> And we are putting our logs of sockstat, iostat 5, vmstat 5,
> netstat 5, dmesg, uname -a on the following URL.
> 
> http://zoo.ee.ntu.edu.tw/~keichii/
> 
> *DRUM ROLL*
> What do you think we can do to make this server survive the 
>   peak load of around 5000 users? :)
> 

[snip several non-interesting ideas]

> * Anything else we can do?

Well first off, telling us which version of FreeBSD this is...

Second, provide a crashdump with debug symbols, and show us
the backtrace.

Third, consider alternatives to MFS since it seems to be a key
factor in your stability problems.  If you just need a pretty
fast /tmp, I would use a softupdates partition as it's probably
more effecient than MFS/MD.

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]


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