Subject: Re: bad performance on Solaris 10
From: Chris Mair <list@1006.org>
To: Robert Lor <Robert.Lor@Sun.COM>
Cc: Josh Berkus <josh@agliodbs.com>, Mark Kirkwood <markir@paradise.net.nz>,
	pgsql-performance@postgresql.org, llonergan@greenplum.com
In-Reply-To: <4434C505.1000205@sun.com>
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	<44346DAA.2080905@paradise.net.nz>
	<200604052135.14326.josh@agliodbs.com>
	<1144303269.3718.4.camel@dell.home.lan>  <4434C505.1000205@sun.com>
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Date: Fri, 07 Apr 2006 21:29:34 +0200
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> >Ok, so I did a few runs for each of the sync methods, keeping all the
> >rest constant and got this:
> >
> >open_datasync      0.7
> >fdatasync          4.6
> >fsync              4.5
> >fsync_writethrough not supported
> >open_sync          0.6
> >
> >in arbitrary units - higher is faster.
> >
> >Quite impressive!
> >
> >
> >  
> >
> Chris,
> Just to make sure the x4100 config is similar to your Linux system, can 
> you verify the default setting for disk write cache and make sure they 
> are both enabled or disabled. Here's how to check in Solaris.
> As root, run "format -e" -> pick a disk -> cache -> write_cache -> display
> 
> Not sure how to do it on Linux though!
> 
> Regards,
> -Robert

I don't have access to the machine for the next few days due to eh...
let's call it firewall accident ;), but it might very well be that it
was off on the x4100 (I know it's on the smaller Linux box).

That together with the bad default sync method can definitely explain
the strangely slow out of box performance I got.

So thanks again for explaining this to me :)

Bye, Chris.