for a configurable number of seconds, spin the disk down. Spin it back
up on the next request.
Notice that the timeout is only armed by a request, so to spin down a
disk you may have to do:
atacontrol spindown ad10 5
dd if=/dev/ad10 of=/dev/null count=1
To disable spindown, set timeout to zero:
atacontrol spindown ad10 0
In order to debug any trouble caused, this code is somewhat noisy on the
console.
Enabling spindown on a disk containing / or /var/log/messages is not
going to do anything sensible.
Spinning a disk up and down all the time will wear it out, use sensibly.
Approved by: sos
916647a52a