Spin down HDD after disk sync or before power off

[Warren Block]

On Wed, 3 Feb 2010, Oliver Fromme wrote:

> Alexander Best wrote:
> > imo this patch takes good care of the problem. would be nice to
> > have it in HEAD.
>
> No -- *Please* make sure that the disks are only spun down
> upon an actual power-off command (i.e. when reboot() is
> called with the RB_POWEROFF flag).  In all other cases the
> disks should keep running.  It's not good to have the disks
> spin down and then immediately spin up again on every
> reboot.

Could you elaborate a little on why that's bad?  It seems like it would 
be similar to a standby/resume action.

Are there any other device drivers that differentiate the reboot and 
poweroff actions that could be used as inspiration or simply shamelessly 
copied in modifying ata-disk?

-Warren Block * Rapid City, South Dakota USA