Re: Loud "pop" coming from hard drive on reboot

[Bodo Eggert]

Tejun Heo <htejun@xxxxxxxxx> wrote:

> This really isn't a regression.  It's been always like that with libata.
>  libata doesn't make devices go into standby mode and shutdown(8) does
> it for libata.  The problem here is that libata does issue
> SYNCHRONIZE_CACHE on shutdown.  So, the sequence of event is...
> 
> 1. shutdown(8) issues SYNCHRONIZE_CACHE followed by STANDBY_NOW
> 2. kernel shutdown starts
> 3. libata shutdown issues SYNCHRONIZE_CACHE
> 4. power goes off
> 
> Some drives seem to spin up at step #3 even when its cache is clean and
> power goes off right after the disk finishes the command.  So, it's
> really bad when it happens - spin down, spin up followed by immediate
> power off.
> 
> SCSI part of the fix is queued in scsi-misc-2.6 tree and libata-dev part
> is acked and waiting to be merged, so the fix will be available in
> 2.6.22.  However, it's disabled by default to remain compatible with the
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> current behavior and requires userland change to fully fix the problem.
  ^^^^^^^^^^^^^^^^
It sounds like the Schilling kind of compatibility: "The old burner destroyed
your disk on buffer underruns, therefore the new thing should do the same
instead of giving you a perfectly readable data disk."

Guys, not destroying hardware is _NOT_ bad!
-- 
Anger, fear, aggression. The Dark Side of the Force are they.
Once you start down the Dark Path, forever will it dominate your destiny.
        -- Jedi Master Yoda
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