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    SubjectRe: [git patch] libata resume fix
    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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