From: Scott Marlowe <smarlowe@g2switchworks.com>
To: Ragnar <gnari@hive.is>
Cc: pgsql-performance@postgresql.org
Subject: Re: Large Database Design Help
Date: Fri, 10 Feb 2006 16:42:25 -0600
Message-ID: <1139611345.22740.151.camel@state.g2switchworks.com> (raw)
In-Reply-To: <1139611194.17929.105.camel@localhost.localdomain>
References: <43EB92DA.2080607@orangekids.org>
<43EC69EA.3010709@logix-tt.com>
<1139611194.17929.105.camel@localhost.localdomain>
On Fri, 2006-02-10 at 16:39, Ragnar wrote:
> On Fri, 2006-02-10 at 11:24 +0100, Markus Schaber wrote:
>
> > For lots non-read-only database workloads, RAID5 is a performance
> > killer. Raid 1/0 might be better, or having two mirrors of two disks
> > each, the first mirror holding system, swap, and the PostgreSQL WAL
> > files, the second one holding the data.
>
> I was under the impression that it is preferable to keep the WAL on
> its own spindles with no other activity there, to take full advantage
> of the sequential nature of the WAL writes.
>
> That would mean one mirror for the WAL, and one for the rest.
> This, of course, may sometimes be too much wasted disk space, as the WAL
> typically will not use a whole disk, so you might partition this mirror
> into a small ext2 filesystem for WAL, and use the rest for files seldom
> accessed, such as backups.
Well, on most database servers, the actual access to the OS and swap
drives should drop to about zero over time, so this is a workable
solution if you've only got enough drives / drive slots for two mirrors.
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: smarlowe@g2switchworks.com, gnari@hive.is
Subject: Re: Large Database Design Help
In-Reply-To: <1139611345.22740.151.camel@state.g2switchworks.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox