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Date: Wed, 17 Oct 2007 17:01:31 -0200
From: Patrick Tracanelli <eksffa@freebsdbrasil.com.br>
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To: kurtseel <kurtseel@primetime.com>
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Cc: freebsd-geom@freebsd.org
Subject: Re: gmirror + ggated question
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kurtseel escreveu:
> 
> I built a mirror of a local drive and a ggated backed device. I ran 
> iozone on it
> and it runs along fine until a certain point when it slows down to a 
> near stand
> still. It doesn't break the mirror or crash the system, but it does slow 
> the system
> down to a near stop.
> I kill the iozone, and a short time later I can login and then :
> 
> # df
> Filesystem            1K-blocks    Used    Avail Capacity  Mounted on
> /dev/mirror/thinkcs1a   1012974  155780   776158    17%    /
> devfs                         1       1        0   100%    /dev
> /dev/mirror/thinkcs1e  85469448 1163474 77468420     1%    /usr
> /dev/mirror/thinkcs1d   4058062   40426  3692992     1%    /var
> [root@ ~/temp]# gmirror status
>         Name    Status  Components
> mirror/thinkc  COMPLETE  ad0
>                         ggate0
> 
> And all seems normal again. Seems like it has to do with big files ...
> This is the same configuration I used in :
> http://bsdtips.utcorp.net/mediawiki/index.php/Mirroring_over_network
> This is where the iozone gets stuck :

Did you try raising send and receive buffers on ggated? I found myself 
confortable with -S and -R around 512k-780k. I didnt, however, did an 
iozone stress test, just a production test (real load) before going 
production.

Try raising the buffer and let us know about your tests. TCP_NODELAY is 
also worth trying.

-- 
Patrick Tracanelli

FreeBSD Brasil LTDA.
(31) 3281-9633 / 3281-3547
316601@sip.freebsdbrasil.com.br
http://www.freebsdbrasil.com.br
"Long live Hanin Elias, Kim Deal!"