Quoting Ralf Mardorf <ralf.mardorf(a)alice-dsl.net>et>:
"All WD external hard drives will spin down
(enter into power saver
mode) after 10 minutes of drive inactivity. Once the drive is accessed
again, the drive will exit from the power saver mode and spin back up.
If it's designed to spin down it's probably also designed to be able
to handle that.
An obvious workaround would be having a cron job doing a 'touch
TempFile' or something similar on the disk once every 5 minutes or so.
- Peder