Date: Thu, 19 Oct 2006 18:53:49 +0200
From: Tobias Brox <tobias@nordicbet.com>
To: "Jim C. Nasby" <jim@nasby.net>
Cc: Tobias Brox <tobias@nordicbet.com>,
	pgsql-performance@postgresql.org
Subject: Re: Swappiness setting on a linux pg server
Message-ID: <20061019165349.GE31916@oppetid.no>
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[Jim C. Nasby - Thu at 11:45:32AM -0500]
> > > The issue with pg_xlog is you don't need bandwidth... you need super-low
> > > latency. The best way to accomplish that is to get a battery-backed RAID
> > > controller that you can enable write caching on.
> > 
> > Sounds a bit risky to me :-)
> 
> Well, you do need to understand what happens if the machine does lose
> power... namely you have a limited amount of time to get power back to
> the machine so that the controller can flush that data out. Other than
> that, it's not very risky.

We have burned ourself more than once due to unreliable raid controllers
...

> quantities of memory. So in your case, 600M wouldn't be pushing things
> much at all. Even 1G wouldn't be that out of the ordinary. Also remember
> that the more memory for shared_buffers, the less for
> sorting/hashes/etc. (work_mem)

What do you mean, a high value for the shared_buffers implicates I
can/should lower the work_mem value?  Or just that I should remember to
have more than enough memory for both work_mem, shared_buffers and OS
caches?  What is a sane value for the work_mem?  It's currently set to
8M.