From mboxrd@z Thu Jan  1 00:00:00 1970
From: Krzysztof Adamski <k@adamski.org>
Subject: Re: It is safe to stop Raid being reshaped
Date: Fri, 30 Dec 2011 09:51:25 -0500
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To: Mattias Wadenstein <maswan@acc.umu.se>
Cc: Mikael Abrahamsson <swmike@swm.pp.se>, Jeremy Thompson <jeremythompson82@gmail.com>, Brad Campbell <brad@fnarfbargle.com>, Asdo <asdo@shiftmail.org>, linux-raid <linux-raid@vger.kernel.org>
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On Fri, 2011-12-30 at 13:16 +0100, Mattias Wadenstein wrote:
> On Fri, 30 Dec 2011, Mikael Abrahamsson wrote:
> 
> > On Thu, 29 Dec 2011, Jeremy Thompson wrote:
> >
> >> I thought about this as well - I have an Enermax 450 in there right now... 
> >> I'll have to look for a higher watt power supply next I guess.
> >
> > Also look at how your feeds are balanced. Some PSUs have two rails, putting 
> > all drives on a single rail causes your load handling capacity to go down 
> > significantly. I recommend getting a single rail PSU as well, well above the 
> > capacity you think you need.
> 
> Not only that, take a good look at both the 5V and 12V specs, and compare 
> them to the draw needed by the drives (and the rest of the system). I've 
> found that the ammount of 5V available varies lots between PSUs, without 
> much correlation with the 12V supply. Which is fine for modern CPUs/GPUs 
> which mostly uses 12V, but drives seem to want quite a bit of 5V too.
> 
> One other common problem with multiple rail PSUs is that often all the 
> useful power connectors (sata/molex) are only on one rail. I wouldn't mind 
> multiple rails if I could actually use all of them for drives.
> 
> For the 24-drive home build I've done, I've actually ended up running two 
> PSUs in parallel (joining ground), but this is hardly something to 
> recommend to anyone sane. ;)

I can give you my recommendation for a power supply based on my box.
The box has 22 drives (all 7200), dual core Phenom II, 8 Gig ram.
The PS is a OCZ ModXstream Pro 700. It has been running for over a year
without showing any problems. In a normal steady state the box draws 260
Watts from the wall as measures by a Kill-A-Watt device.

K