Re: [PERFORM] syslog slowing the database?

From: Richard Huxton <dev(at)archonet(dot)com>
To: Greg Spiegelberg <gspiegelberg(at)cranel(dot)com>, PgSQL Performance ML <pgsql-performance(at)postgresql(dot)org>, Postgres Admin List <pgsql-admin(at)postgresql(dot)org>
Subject: Re: [PERFORM] syslog slowing the database?
Date: 2004-03-09 21:34:35
Message-ID: 200403092134.35905.dev@archonet.com
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On Tuesday 09 March 2004 20:29, Greg Spiegelberg wrote:

> iostat reported ~2000 blocks written every 2
> seconds to the DB file system.
>
> I turned syslog off to see if it was blocking anything and in the
> past couple minutes 1GB has been restored and iostat reports ~35,000
> blocks written every 2 seconds to the DB file system.

> Can anyone confirm this for me?

If syslog is set to sync after every line and you're logging too much then it
could slow things down as the disk heads shift back and fore between two
areas of disk. How many disks do you have and in what configuration?

Also - was PG logging a lot of info, or is some other application the culprit?

Tip: put a minus "-" in front of the file-path in your syslog.conf and it
won't sync to disk after every entry.

--
Richard Huxton
Archonet Ltd

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