From: Bill Moran <wmoran@collaborativefusion.com>
To: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Background writer underemphasized ...
Date: Wed, 16 Apr 2008 16:07:24 -0400
Message-ID: <20080416160724.7605ffdb.wmoran@collaborativefusion.com> (raw)
In-Reply-To: <Pine.GSO.4.64.0804161546310.27404@westnet.com>
References: <480619CA.2080904@geizhals.at>
<20080416144335.04368b67.wmoran@collaborativefusion.com>
<Pine.GSO.4.64.0804161546310.27404@westnet.com>
In response to Greg Smith <gsmith@gregsmith.com>:
> On Wed, 16 Apr 2008, Bill Moran wrote:
>
> >> bgwriter_delay = 10000ms # 10-10000ms between rounds
> >> bgwriter_lru_maxpages = 1000 # 0-1000 max buffers written/round
> > Have you watched closely under load to ensure that you're not seeing a
> > huge performance hit every 10s when the bgwriter kicks off?
>
> bgwriter_lru_maxpages = 1000 means that any background writer pass can
> write at most 1000 pages = 8MB. Those are buffered writes going into the
> OS cache, which it will write out at its own pace later. That isn't going
> to cause a performance hit when it happens.
>
> That isn't the real mystery though--where's the RAID5 rant I was expecting
> from you?
Oh crap ... he _is_ using RAID-5! I completely missed an opportunity to
rant!
blah blah blah ... RAID-5 == evile, etc ...
--
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/
wmoran@collaborativefusion.com
Phone: 412-422-3463x4023
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To: pgsql-performance@postgresql.org
Cc: wmoran@collaborativefusion.com, gsmith@gregsmith.com
Subject: Re: Background writer underemphasized ...
In-Reply-To: <20080416160724.7605ffdb.wmoran@collaborativefusion.com>
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