Date: Mon, 24 Apr 2006 13:29:17 +1200
From: Mark Kirkwood <markir@paradise.net.nz>
Subject: Re: Hardware: HP StorageWorks MSA 1500
In-reply-to: <7F10D26ECFA1FB458B89C5B4B0D72C2B3E4009@sesrv12.wirelesscar.com>
To: Mikael Carneholm <Mikael.Carneholm@WirelessCar.com>
Cc: Alex Hayward <xelah-pgsql@xelah.com>,
	Pgsql performance <pgsql-performance@postgresql.org>
Message-id: <444C29ED.2070901@paradise.net.nz>
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References: <7F10D26ECFA1FB458B89C5B4B0D72C2B3E4009@sesrv12.wirelesscar.com>

Mikael Carneholm wrote:
> Your numbers seem quite ok considering the number of disks. We also get
> a 256Mb battery backed cache module with it, so I'm looking forward to
> testing the write performance (first using ext3, then xfs). If I get the
> enough time to test it, I'll test both raid 0+1 and raid 5
> configurations although I trust raid 0+1 more.
> 
> And no, it's not the cheapest way to get storage - but it's only half as
> expensive as the other option: an EVA4000, which we're gonna have to go
> for if we(they) decide to stay in bed with a proprietary database. With
> postgres we don't need replication on SAN level (using slony) so the MSA
> 1500 would be sufficient, and that's a good thing (price wise) as we're
> gonna need two. OTOH, the EVA4000 will not give us mirroring so either
> way, we're gonna need two of whatever system we go for. Just hoping the
> MSA 1500 is reliable as well...
> 
> Support will hopefully not be a problem for us as we have a local
> company providing support, they're also the ones setting it up for us so
> at least we'll know right away if they're compentent or not :)
> 

If I'm reading the original post correctly, the biggest issue is likely 
to be that the 14 disks on each 2Gbit fibre channel will be throttled to 
200Mb/s by the channel , when in fact you could expect (in RAID 10 
arrangement) to get about 7 * 70 Mb/s = 490 Mb/s.

Cheers

Mark