From: John Lister <john.lister@kickstone.co.uk>
To: Jan Nielsen <jan.sture.nielsen@gmail.com>
Cc: sthomas@peak6.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Configuration Recommendations
Date: Thu, 03 May 2012 07:54:10 +0100
Message-ID: <4FA22B92.6050103@kickstone.co.uk> (raw)
In-Reply-To: <CANxH4hE2WTvLJeVXz-o4npvOdoHvh1GLQjt=eYjErSQKdo7anQ@mail.gmail.com>
References: <CANxH4hGW+RYXsB8BdAY9hoGzje26EapX1H6H-jrNZAMQKZ+hMQ@mail.gmail.com>
<4F96FFE1.2030809@peak6.com>
<4F97ABBB.1000708@kickstone.co.uk>
<4F986CAC.4060904@peak6.com>
<CANxH4hE2WTvLJeVXz-o4npvOdoHvh1GLQjt=eYjErSQKdo7anQ@mail.gmail.com>
On 03/05/2012 03:10, Jan Nielsen wrote:
>
> 300GB RAID10 2x15k drive for OS on local storage
> */dev/sda1 RA* 4096
> */dev/sda1 FS* ext4
> */dev/sda1 MO*
>
> 600GB RAID 10 8x15k drive for $PGDATA on SAN
> *IO Scheduler sda* noop anticipatory deadline [cfq]
> */dev/sdb1 RA* 4096
> */dev/sdb1 FS* xfs
> */dev/sdb1 MO* allocsize=256m,attr2,logbufs=8,logbsize=256k,noatime
>
> 300GB RAID 10 2x15k drive for $PGDATA/pg_xlog on SAN
> *IO Scheduler sdb* noop anticipatory deadline [cfq]
> */dev/sde1 RA* 4096
> */dev/sde1 FS* xfs
> */dev/sde1 MO* allocsize=256m,attr2,logbufs=8,logbsize=256k,noatime
> *
I was wondering if it would be better to put the xlog on the same disk
as the OS? Apart from the occasional log writes I'd have thought most OS
data is loaded into cache at the beginning, so you effectively have an
unused disk. This gives you another spindle (mirrored) for your data.
Or have I missed something fundamental?
--
www.pricegoblin.co.uk
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To: pgsql-performance@postgresql.org
Cc: john.lister@kickstone.co.uk, jan.sture.nielsen@gmail.com, sthomas@peak6.com
Subject: Re: Configuration Recommendations
In-Reply-To: <4FA22B92.6050103@kickstone.co.uk>
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