Windows

Power Management in 2003 isn't all that reliable all you can be sure it will do is shut down the HDD's but they may not restart when required.

This is one thing that I always disable on any server that I provide as the customers believe that it is a hardware problem with the constant reboots to get the Arrays running again than a Software problem.

Col

First off if it's a server why do you want to power down the HDDs? Servers are to provide services to users. Powering down the HDDs essentially take the server offline [unavailable]. This assume that your logged in with some user account 24/7. The way you bring them back online is is to create activity such as moving the mouse or pressing a key on the keyboard. Staying logged on with an user account is a serious security issue.

If your concerned with power sonsuption and HDD life have to decide what the server is for. Normally, hardware lifecycle is a planned feature that takes in consideration HDD MTBF and replacements are planned before the mfg's MTBF for the HDD.