From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Shubert Subject: Re: RAID Class Drives` Date: Mon, 22 Mar 2010 09:29:12 -0700 Message-ID: References: <7c2a12e21003190943t546ade49u2294310ed7d9921e@mail.gmail.com> <38.31.05956.E4417AB4@cdptpa-omtalb.mail.rr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <38.31.05956.E4417AB4@cdptpa-omtalb.mail.rr.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Leslie Rhorer wrote: >> -----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` >> >> 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. >> Google's study of >100,000 disks over 9 months or so >> suggests that >> hotter drives don't fail much more often: >> >> ". . . 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) >> >> "We can conclude that at moderate temperature ranges it is likely th= at >> there are other effects which affect failure rates much more strongl= y >> than temperatures do." (page 6) >> >> 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). >=20 > 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 E= thyl > 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 resul= t in > moderately severe burns. For most mechanical systems however, 80C is= not > particularly hot. Many solid state electronics systems can withstand= 80C > internal temperatures indefinitely. An average healthy adult human b= eing > 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 e= mploys > a refrigerated fluid cooling system or a Peltier junction to actively= cool > 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 c= old in > my house right now, because I have the heat shut off to save money, y= et the > coolest drive in my arrays - which have very effective forced air sys= tems > built in to them - are 31C. Most are over 33C by a wide margin. Com= e > summer, all of them will be over 40C. >=20 > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >=20 I had a few drives running at about 55C for a couple years, with no=20 failures (knock wood). These were used drives before being put into tha= t=20 environment, so they arguably had already survived the "infant mortalit= y=20 syndrome" that the google study identified. Would I recommend running=20 drives at 55C? No, but I wouldn't be too concerned about it either. =46WIW. --=20 -Eric 'shubes' -- 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