Re: storage fixup laptop model dependent ?

[Robert Hancock <hancockrwd@gmail.com>]

On 12/20/2009 10:34 PM, Tejun Heo wrote:
> (cc'ing Kay and Lennart.  Hello.)
>
> This thread was discussing about drives which unload heads too
> frequently.  These problems happen mostly on laptops.  Either mobile
> HDDs default to too aggressive power saving or laptop firmware
> configures them that way.  Anyways, some drives end up unoading and
> reloading the head more quite a few times per minute.
>
> Mobile drives tend to have higher load cycle limits than desktop ones
> and this information can be found from drive specs published on vendor
> websites.  Most modern mobile ones seem to be rated for 600,000
> cycles.  Unfortunately, with 5 unloads per minute, the drive will
> reach its rated limit only after 83 days of uptime.  IOW, if you use
> the machine 8hrs per day, it will expire before one year has passed.
>
> Very short unload timeout is inherently dangerous as idle IO patterns
> can differ depending on a lot of things and these rapid load/unload
> cycles can happen under various different configurations (it happens
> under windows too).  When this problem first appeared, I thought
> vendors would realize the danger and it would go away sooner or later.
>
> Expecting it to be a temporary problem, I wrote up a simple script
> named storage-fixup which matches the system and harddrive model and
> issues safe powersave configuration.  This is a crude and sub-optimal
> solution which doesn't scale too well.  Many of those configurations
> wouldn't require such APM adjustments and a lot of configurations
> where APM re-configuration is required are out there killing their
> drives.
>
> A proper solution would be....
>
> * Build database of load cycle limits and useable APM values on drive
>    models.  The former shouldn't be difficult.  Each vendor carries
>    only a few product lines at any given time and publish datasheets on
>    the webpage.  Plus, all the mobile drives I've seen are rated for
>    600,000 cycles.  The latter may be a bit more tricky.  Depending on
>    drive model, certain APM values simply don't work (e.g. 255 means
>    max power by spec but some firmwares wrap the value and recognize it
>    as min power), some values overheats the device and so on.  In most
>    cases the value 254 seems safe tho.  storage-fixup.conf should be
>    useable as the source for useable values, I think.
>
> * Monitor load cycle count by smart commands and if it continues to
>    increase at an excessive rate (e.g. such that it reduces uptime to
>    under a year), warn the user and configure higher APM value.
>
> As this problem mostly happens on laptops, I think it's probably best
> to handle this from the new desktop disk management thing so that the
> user can be warned.  Do you think it's feasible to handle this from
> devkit?

I think that would be a good approach if we can do it. The situation 
definitely isn't ideal though. Has anyone approached any of the laptop 
manufacturers or drive manufacturers regarding this problem? I suspect 
there's probably a lack of awareness about it. (Though it could just be 
that Windows usually accesses the drive so often that it just never 
really reaches the unload timeouts..)