Messages in this thread | | | Date | Tue, 14 Nov 2006 10:30:06 +0100 (MET) | From | Jan Engelhardt <> | Subject | Re: HD head unloads (was: Re: AHCI power saving) |
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On Nov 14 2006 01:43, Henrique de Moraes Holschuh wrote: >On Mon, 13 Nov 2006, Pavel Machek wrote: >>On Mon 2006-11-13 12:58:10, Mark Lord wrote: >>>Jeff Garzik wrote: >>>>Andi Kleen wrote: >>>> >>>>>How does it shorten its life? >>>> >>>>Parks your hard drive heads many thousands of times more often than it >>>>does without the aggressive PM features. >>> >>>Spinning-down would definitely shorten the drive lifespan. Does >>>it do that? >> >>Not on my machine. > >Heck, given just how much a ThinkPad T43 BIOS will attempt to do it for you, >consider yourself lucky if the X60 behaves differently. When I thought of >monitoring the head unload counter through SMART on mine, my HD was already >beyond 14k unloads... and the notebook had been powered up less than 100 >times :p
Let me jump in here. Short info: Toshiba MK2003GAH 1.8" 20GB PATA harddisk, in a Sony Vaio U3 (x86, gray-blue PhoenixBIOS). If idle for more than 5 secs, unloads. Even when not inside any OS, which really sets me off. So I wrote a quick workaround hack for Linux, http://tinyurl.com/y3qs6g It reads a predefined amount of bytes (just as much to not cause slowdown yet still cause it to not unload) from the disk at fixed intervals.
>The BIOS likes to set the drive APM mode to something other than "off", and >in many drives (well, Hitachi ones at least), that means the drive will be >happy to unload heads every chance it gets, so as to be able to power off >the head assembly motion drive. > >> > Parking heads is more like just doing some extra (long) seeks. > >Long seeks don't lift the head assembly off the plates, head unloads do. >And head unloads will also power down some stuff in laptop HDs, seeks don't >do that either.
Parking heads is worse than a seek - it takes more time to reload it than to seek to the other side.
>And even old-style parking places the heads on a different surface than the >data area. That's a lot different from seeks no matter how one looks at it. > >> > Is this documented somewhere as being a life-shortening action? > >Yes, although not often with that many words. > >For example, a Hitachi Travelstar 5k100 is rated for 600k load/unload >cycles, and 20k emergency load/unload cycles (each emergency unload counts >as 30 normal unloads, but the tech docs say it is about 100 times more >stressfull to the drive). It is in the public drive datasheet, along with >other important information, such as that the drive needs to spin down often >(no less than once every 48h) or its lifespan will be shortened. > >A typical desktop HD can probably survive a lot less head load/unload >cycles and spin up/down cycles than that. > >-- > "One disk to rule them all, One disk to find them. One disk to bring > them all and in the darkness grind them. In the Land of Redmond > where the shadows lie." -- The Silicon Valley Tarot > Henrique Holschuh >-
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