Re: [PATCH] sd: implement stop_on_shutdown

[Tejun Heo <htejun@gmail.com>]

Darrick J. Wong wrote:
> Tejun Heo wrote:
>> sd doesn't stop (unload head) on shutdown.  This behavior is necessary
>> for multi initiator cases.  Unloading head by powering off stresses
>> the drive and sometimes produces distinct clunking noise which
>> apparently disturbs users considering multiple reports on different
>> distributions.  halt(8) usually puts the drives to sleep prior to
>> shutdown but the implementation is fragile and it doesn't work with
>> sleep-to-disk.
> 
> I wonder if this sort of thing (cache flush + spin down) is the sort of
> thing that ought to be done to near-line storage at suspend time too,
> though one would want allow_restart = 1 before doing such a thing.

For ATA, it's currently being done inside libata proper (a bit ugly).
It would be nice to have those implemented at sd layer but I wonder how
useful it's going to be for actual SCSI devices.  Do people actually
suspend using SCSI?  If it's useful at the SCSI layer, I can implement
and test it with SATA devices here.

Thanks.

-- 
tejun