FreeNAS is a pretty great (and free!) Network Attached Storage system. Recently, it was updated to version 9.3 which contained a lot of great improvements including automatic updates over the network. (Previously, the upgrade process was manual and kind of a pain in the neck.)
Unfortunately, FreeNAS isn’t very good at the power-saving thing. (read: spinning down your hard drives when they’re not being used.) And prior to FreeNAS 9.x, it was pretty easy to get the drives to go into Standby mode using a few commands. But again, FreeNAS has changed the default install to put the system log (which it writes somewhat regularly to) on the very drives you’re trying to spin down.
Fortunately, there is a fix.