Re: [git patch] libata resume fix

[Jens Axboe]

On Tue, Jun 06 2006, Tejun Heo wrote:
> Hi, Jens.
> 
> Jens Axboe wrote:
> >On Wed, May 31 2006, Robert Hancock wrote:
> >>Bill Davidsen wrote:
> >>>The trade-off is that if I have a 15k rpm SCSI drive, it would take a 
> >>>lot of design changes to make it spin up quickly, and improve a function 
> >>>which is usually done on a server once every MTBF when replacing the 
> >>>failed unit.
> >>>
> >>>I think the majority of very large or very fast drives are in systems 
> >>>which don't (deliberately) power cycles often, in rooms where heat is an 
> >>>issue. And to spin up quickly take a larger power supply... 30 sec is 
> >>>fine with most users.
> >>>
> >>>Couldn't find a spin-up time for the new Seagate 750GB drive, but the 
> >>>seek sure is fast!
> >>I wouldn't guess that even a 15K drive would take nearly that long. For 
> >>boot time on servers it doesn't matter much though, disk spinup time is 
> >
> >I do use a 15K rpm drive in my workstation (hello git!), and the spin up
> >really isn't that bad. Less than 10 seconds for the actual spin up, I
> >would say.
> 
> Can you measure spin up time for your 15k's?  Some controllers can't 
> catch the first D2H FIS after POR and have to wait unconditionally for 
> spin up for hotplug & resuming from suspend.  Currently 8 sec wait is 
> used but it seems insufficient for your drives.  Failing to spinup in 
> that 8 secs would probably result in timeout of the first reset attempt 
> and retrial - which currently takes > 30 secs.
> 
> Spin-up time can be measured by first issuing STANDBY and then time how 
> long IDLE IMMEDIATE takes, I think.

The 15K RPM is a SCSI drive, I haven't seen any SATA 15K rpm drives yet.
I have the same model in another box, I can measure spinup with
START_STOP unit there. I will do so later today, when I fire it up, if
you still want to know?

-- 
Jens Axboe

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