From: | Mark Mielke <mark(at)mark(dot)mielke(dot)cc> |
---|---|
To: | Matthew <matthew(at)flymine(dot)org> |
Cc: | pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: How to allocate 8 disks |
Date: | 2008-03-03 14:48:49 |
Message-ID: | 47CC0FD1.7090404@mark.mielke.cc |
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Lists: | pgsql-performance |
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(at)mielke(dot)cc>
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