From: Mark Mielke <mark@mark.mielke.cc>
To: Matthew <matthew@flymine.org>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: How to allocate 8 disks
Date: Mon, 03 Mar 2008 09:48:49 -0500
Message-ID: <47CC0FD1.7090404@mark.mielke.cc> (raw)
In-Reply-To: <Pine.LNX.4.64.0803031206340.20402@aragorn.flymine.org>
References: <1204285894.11773.33.camel@franck-gusty>
<dcc563d10802290613v482f52dr43ea95b52886de31@mail.gmail.com>
<1204296705.11773.51.camel@franck-gusty>
<Pine.GSO.4.64.0802291019570.28452@westnet.com>
<47C88826.4040209@paradise.net.nz>
<47C99B3E.4010606@emolecules.com>
<20080301130347.0832b323@commandprompt.com>
<47C9D05C.3040908@emolecules.com>
<Pine.LNX.4.64.0803031206340.20402@aragorn.flymine.org>
Matthew wrote:
> On Sat, 1 Mar 2008, Craig James wrote:
>> Right, I do understand that, but reliability is not a top priority in
>> this system. The database will be replicated, and can be reproduced
>> from the raw data.
>
> So what you're saying is:
>
> 1. Reliability is not important.
> 2. There's zero write traffic once the database is set up.
>
> If this is true, then RAID-0 is the way to go. I think Greg's options
> are good. Either:
>
> 2 discs RAID 1: OS
> 6 discs RAID 0: database + WAL
>
> which is what we're using here (except with more discs), or:
>
> 8 discs RAID 10: everything
Has anybody been able to prove to themselves that RAID 0 vs RAID 1+0 is
faster for these sorts of loads? My understanding is that RAID 1+0 *can*
reduce latency for reads, but that it relies on random access, whereas
RAID 0 performs best for sequential scans? Does PostgreSQL ever do
enough random access to make RAID 1+0 shine?
Curious.
Thanks,
mark
--
Mark Mielke <mark@mielke.cc>
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To: pgsql-performance@postgresql.org
Cc: mark@mark.mielke.cc, matthew@flymine.org
Subject: Re: How to allocate 8 disks
In-Reply-To: <47CC0FD1.7090404@mark.mielke.cc>
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