From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Leslie Rhorer" Subject: RE: RAID Class Drives` Date: Mon, 22 Mar 2010 01:55:07 -0500 Message-ID: <38.31.05956.E4417AB4@cdptpa-omtalb.mail.rr.com> References: <7c2a12e21003190943t546ade49u2294310ed7d9921e@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <7c2a12e21003190943t546ade49u2294310ed7d9921e@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: 'Aryeh Gregor' , 'John Robinson' Cc: 'Joachim Otahal' , linux-raid@vger.kernel.org List-Id: linux-raid.ids > -----Original Message----- > From: linux-raid-owner@vger.kernel.org [mailto:linux-raid- > owner@vger.kernel.org] On Behalf Of Aryeh Gregor > Sent: Friday, March 19, 2010 11:43 AM > To: John Robinson > Cc: Joachim Otahal; linux-raid@vger.kernel.org > Subject: Re: RAID Class Drives` >=20 > On Fri, Mar 19, 2010 at 4:15 AM, John Robinson > wrote: > > Do you have a reference for this? Most drives' operating temperatur= e > range > > is specified up to 55=B0C, sometimes higher for enterprise drives, = without > any > > indication (apart from common sense perhaps) that running them this= hot > > reduces lifespan. >=20 > Google's study of >100,000 disks over 9 months or so > suggests that > hotter drives don't fail much more often: >=20 > ". . . failures do not increase when the average temperature > increases. In fact, there is a clear trend showing that lower > temperatures are associated with higher failure rates. Only at very > high temperatures is there a slight reversal of this trend." (page 5 > of PDF) >=20 > "We can conclude that at moderate temperature ranges it is likely tha= t > there are other effects which affect failure rates much more strongly > than temperatures do." (page 6) >=20 > They were using SATA and PATA consumer drives, 5400 RPM to 7200 RPM, > 80 to 400 GB, put into production in or after 2001 (from page 3). First of all, not what they call "high" temperatures in the paper are not really very high. Eighty C is roughly the boiling point of Eth= yl Alcohol, and in human terms this is considered quite hot. Immersion of= body tissues in a large volume of 80C water for several seconds will result = in moderately severe burns. For most mechanical systems however, 80C is n= ot particularly hot. Many solid state electronics systems can withstand 8= 0C internal temperatures indefinitely. An average healthy adult human bei= ng has a body core temperature of 37C, and a device with a 40C surface temperature is barely warm to the touch. It is not hot. Unless one emp= loys a refrigerated fluid cooling system or a Peltier junction to actively c= ool it, no drive system is ever going to be less than 30C if the room temperature is anything other than uncomfortably cold. It's rather col= d in my house right now, because I have the heat shut off to save money, yet= the coolest drive in my arrays - which have very effective forced air syste= ms built in to them - are 31C. Most are over 33C by a wide margin. Come summer, all of them will be over 40C. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html