Message-ID: <4C20BD33.1040908@magwerks.com>
Date: Tue, 22 Jun 2010 08:40:03 -0500
From: Justin Graf <justin@magwerks.com>
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To: =?utf-8?Q?_Grzegorz_Ja=C5=9Bkiewicz_<gryzman@gmail.com>?=
CC: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: raid10 write performance
References: <AANLkTinbKXufTYhNuhNaOW2kWM-simIL3dg0uFX7Ij6g@mail.gmail.com>
In-Reply-To: <AANLkTinbKXufTYhNuhNaOW2kWM-simIL3dg0uFX7Ij6g@mail.gmail.com>
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On 6/22/2010 4:31 AM, Grzegorz Jaśkiewicz wrote:
> Hi folks,
>
> is there a general problem with raid10 performance postgresql on it?
> We see very low performance on writes (2-3x slower than on less
> performant servers). I wonder if it is solely problem of raid10
> configuration, or if it is postgresql's thing.
>    

RAID 10 is the commonly suggested layout for DB's as its performance to 
redundancy is good.
The question that begs to be ask is what is the IO layout on the other 
servers your comparing against.


> Would moving WAL dir to separate disk help potentially ?
>    

Yes it can have a big impact.
http://www.westnet.com/~gsmith/content/postgresql/TuningPGWAL.htm
http://wiki.postgresql.org/wiki/Performance_Analysis_Tools

http://wiki.postgresql.org/wiki/Performance_Optimization


> We're running centos 5.4, and server config is:
>
> x3550 M2, xeon 4c e5530 2.4ghz , 6GB of ram
> disks: ibm 300gb 2.5 SAS
>
> raid: serveRAID M5014 SAS/SATA controller
>
> strip size is the default 128k
>
>
> thanks.
>
>    


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