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    SubjectRe: howto spin down a SCSI HD?
    On Thu, 6 Jan 2000, Andreas Bombe wrote:
    > On Wed, Jan 05, 2000 at 10:28:43AM -0500, Richard B. Johnson wrote:
    > > On Wed, 5 Jan 2000 wrote:
    > >
    > > > I'm getting crazy by the sound of my 3 1Gb SCSI hd's
    > > > how can i spin them down so they make less noise?
    > >
    > > The START/STOP unit command (0x1b) will, with some devices, shut down
    > > the drive motor. However, this command is optional and not implemented
    > > on all drives.
    > And it is probably not best practice to spin down SCSI disks
    > often. Unlike IDE disks, SCSI disks are targetted at the server
    > market where disks are ideally running 24 hours a day.

    This is not true any more. If there's both a SCSI and IDE
    model of the same hard drive, you can bet that they both
    use the exact same drive mechanics. The only exception
    here are the ultra-cheap-cut-all-corners IDE-only drives
    and the rediculously-high-end SCSI-only drives...

    What _is_ true, however, is that you cannot just turn off
    a hard drive that's been running 24x7 for ages. When a
    disk is turned off its heads go to the `parking zone', an
    area of the disk which has a wavey surface so that the
    heads can get rid of the dust they gathered without getting
    stuck to the surface (sticktion).

    However, a 24x7 drive often has gathered so much cruft on
    the heads that it'll stick even in the parking zone. The
    solution is to do a short (30 sec) poweroff and get running
    again for a few minutes before the long poweroff. That time
    the heads can shake off most of their dust without getting
    the time to stick...

    > This might have changed with current disks where IDE and SCSI versions

    It has, as usual all the rules have changed :)


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