Date: Wed, 3 Feb 2010 20:43:21 -0700 (MST) From: Warren Block <wblock@wonkity.com> To: Erich Dollansky <erich@alogreentechnologies.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Spin down HDD after disk sync or before power off Message-ID: <alpine.BSF.2.00.1002031946340.11182@wonkity.com> In-Reply-To: <201002041009.05222.erich@alogreentechnologies.com> References: <201002031343.o13Dhj7i052507@lurza.secnetix.de> <alpine.BSF.2.00.1002031328060.9787@wonkity.com> <201002041009.05222.erich@alogreentechnologies.com>
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On Thu, 4 Feb 2010, Erich Dollansky wrote:
> let me do.
>
> On 04 February 2010 am 04:44:04 Warren Block wrote:
>> On Wed, 3 Feb 2010, Oliver Fromme wrote:
>>
>>> Alexander Best wrote:
>>> No -- *Please* make sure that the disks are only spun down
>>> upon an actual power-off command (i.e. when reboot() is
>>
>> Could you elaborate a little on why that's bad? It seems like it would
>> be similar to a standby/resume action.
>>
> every disk has a limited number of restarts before it dies.
Okay. For future reference, here are the numbers I've seen:
power cycles (Seagate): 50,000 lifetime
normal head load/unload (Hitachi): 600,000 lifetime
emergency head load/unload (Hitachi): 20,000 lifetime
> In case of a reboot, it is already known when the command is given that the machine will restart without being powered of.
>
> If you spin-down the disk, you lose one start cycle.
>
> It is not that important but if it can be done with just one if, please, just do it.
AFAICT ad_shutdown can't tell whether it's called for a reboot or a
poweroff, it's just told to "shut down". So maybe it's one if, but it's
somewhere above ata-disk.c but below reboot(RB_POWEROFF).
-Warren Block * Rapid City, South Dakota USA
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