Leslie Rhorer wrote:
-----Original Message-----
From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-
owner@xxxxxxxxxxxxxxx] On Behalf Of Aryeh Gregor
Sent: Friday, March 19, 2010 11:43 AM
To: John Robinson
Cc: Joachim Otahal; linux-raid@xxxxxxxxxxxxxxx
Subject: Re: RAID Class Drives`
On Fri, Mar 19, 2010 at 4:15 AM, John Robinson
<john.robinson@xxxxxxxxxxxxxxxx> wrote:
Do you have a reference for this? Most drives' operating temperature
range
is specified up to 55°C, 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
<http://labs.google.com/papers/disk_failures.html> 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 that
there are other effects which affect failure rates much more strongly
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).
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 Ethyl
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 not
particularly hot. Many solid state electronics systems can withstand 80C
internal temperatures indefinitely. An average healthy adult human being
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 employs
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 cold 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 systems
built in to them - are 31C. Most are over 33C by a wide margin. Come
summer, all of them will be over 40C.
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I had a few drives running at about 55C for a couple years, with no
failures (knock wood). These were used drives before being put into that
environment, so they arguably had already survived the "infant mortality
syndrome" that the google study identified. Would I recommend running
drives at 55C? No, but I wouldn't be too concerned about it either.
FWIW.
--
-Eric 'shubes'
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