From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Re: Samsung F1 RAID Class SATA/300 1TB drives Date: Thu, 04 Nov 2010 11:30:48 +0000 Message-ID: <4CD29968.9010305@anonymous.org.uk> References: <61.E7.19545.3D73FCC4@cdptpa-omtalb.mail.rr.com> <4CD19603.4060308@tmr.com> <4CD21261.8090701@anonymous.org.uk> <4CD28C2F.8010104@seoss.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4CD28C2F.8010104@seoss.co.uk> Sender: linux-raid-owner@vger.kernel.org To: Tim Small Cc: Bill Davidsen , 'Linux-RAID' List-Id: linux-raid.ids On 04/11/2010 10:34, Tim Small wrote: > On 04/11/10 01:54, John Robinson wrote: >> operating power is 7W, the maximum transition power (whatever that is) >> is 40W - yes, 40W > > I'd guess this is either during spin-up, (or spin speed change if > enabled), or possibly even the "inrush" current when power is first > applied to the device (i.e. only for a few milliseconds when the machine > is turned on), and so probably wouldn't cause much of a problem unless. Yes, reading the spec more closely indicates that this transition power is the drive waking up from its lowest power-saving mode, so it's spinning up the discs, so that's not going to be happening much. In second place after spin-up events, from the same spec, we have peak power during random reads of 24W, and 26W for writes, still more than 3 times the average operating power. I take "random reads" to mean lots of seeks, so as Bill said, heavy seeking could be rather rough on a PSU. Cheers, John.