Message-ID: <47DF9278.70605@postnewspapers.com.au>
Date: Tue, 18 Mar 2008 18:59:20 +0900
From: Craig Ringer <craig@postnewspapers.com.au>
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To: Andrej Ricnik-Bay <andrej.groups@gmail.com>
Cc: Peter Koczan <pjkoczan@gmail.com>,
	pgsql-performance@postgresql.org
Subject: Re: What is the best way to storage music files in Postgresql
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	<47DCBD63.9050109@postnewspapers.com.au>	
	<4544e0330803171101g680ffa5bj8ac32908a9f3dfb5@mail.gmail.com>	
	<8fb205ea0803171139h63b55fdrf62776851583a74d@mail.gmail.com>	
	<4544e0330803172026h3eae59a1u8914bda1a5a95bb5@mail.gmail.com>
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Andrej Ricnik-Bay wrote:

> In my testing I found that once you hit 10 spindles in a RAID5 the
> differences between it and a RAID10 started to become negligible
> (around 6% slower on writes average with 10 runs of bonnie++ on
> 10 spindles) while the read speed (if you're doing similar amounts
> of reads &  writes it's a fair criterion) were in about the 10% region
> faster.  With 24 spindles I couldn't see any difference at all. Those
> were 73GB 15K SCAs, btw, and the SAN connected via 2GB fibre.

Isn't a 10 or 24 spindle RAID 5 array awfully likely to encounter a
double disk failure (such as during the load imposed by rebuild onto a
spare) ?

I guess if you have good backups - as you must - it's not that big a
deal, but I'd be pretty nervous with anything less than RAID 6 or RAID 10 .

--
Craig Ringer