Can I shut down disks on ProLiant with RAID array?

[oldtrlrnr]

I have a couple of ProLiant DL380 G3 servers with SmartArray 5i RAID controllers and RAID-5 arrays; OS is Windows Server 2003/SP2. I'd like to be able to set the power management features in Windows, to shut down the hard drives after a certain time interval. It doesn't work - the disks never power down. Device Mgr shows all drivers installed & working OK, but maybe I need another ACPI driver - the only ones I have are shown under System Devices, "ACPI Fixed Feature Button" and "ACPI Thermal Zone". Under Computer it shows "ACPI Multiprocessor PC". I'm suspecting that the level of indirection imposed by the SmartArray controller precludes power mgmt of the disk drives. Wonder if anyone has been able to get the disks to shut down according to Windows power mgmt policy on these servers.