Enable parity spindown after update

[PhracturedBlue]

After running snapraid sync/scrub, force the parity HDD to spindown (assuming the spindown configuration option is set). My parity disks are on USB, and do not respond to hdparm -S (so I cannot configure automatic spindown) but they do respond to hdparm -y to force an immediate spindown.

This solution is Linux (Unix?) specific as it uses sync, hdparm, and df commands. I am not aware of a portable way of implementing these options.

[Chronial]

Would #50 address your use-case?

[PhracturedBlue]

yes, that would work great