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    SubjectRe: [Hdaps-devel] Re: Head parking (was: IBM HDAPS things are looking up)
    Date
    Model: HTS548080M9AT00 (Hitachi)
    Laptop: T42.

    segfault:/home/spstarr# ./a /dev/hda
    head parked

    Seems to park, heard it click :)

    Shawn.

    On July 7, 2005 04:48, Jens Axboe wrote:
    > On Thu, Jul 07 2005, Lenz Grimmer wrote:
    > > -----BEGIN PGP SIGNED MESSAGE-----
    > > Hash: SHA1
    > >
    > > Hi,
    > >
    > > Jens Axboe wrote:
    > > > ATA7 defines a park maneuvre, I don't know how well supported it is
    > > > yet though. You can test with this little app, if it says 'head
    > > > parked' it works. If not, it has just idled the drive.
    > >
    > > Great! Thanks for digging this up - it works on my T42, using a Fujitsu
    > > MHT2080AH drive:
    > >
    > > lenz@metis:~/work/ibm_hdaps> sudo ./headpark /dev/hda
    > > head parked
    > >
    > > Judging from the sound the drive makes, this is the same operation that
    > > the windows tool performs.
    >
    > Very cool, I wasn't sure if this was a 'new' feature waiting to be
    > implemented in drives or if ata7 just documented existing use in some
    > drives.
    >
    > How long did the park take? Spec states it can take up to 500ms.
    >
    > > However, the head does not remain parked for a very long time,
    > > especially if there is a lot of disk activity going on (I tested it by
    > > running a "find /" in parallel). The head parks, but leaves the park
    > > position immediately afterwards again. I guess now we need to find a way
    > > to "nail" the head into the parking position for some time - otherwise
    > > it may already be on its way back to the platter before the laptop hits
    > > the ground...
    >
    > The head just remains parked until the next command is issued. This
    > needs to be combined with some ide help, to freeze the queue. Perhaps
    > some sysfs file so you could do
    >
    > # echo park > /sys/block/hda/device/head_state
    >
    > Or whatever, at least just exposing this possibility so that the drive
    > internally can block future io until a 'resume' command is issued.
    -
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