Mac Mini using RAID won't sleep

Question

I have an Intel Mac Mini with a 100GB internal drive and a 250GB external Firewire drive (miniStack v2). I have configured it so that the internal drive (sans a small Boot Camp partition) is in a RAID1 mirror with the first partition of the external drive. When I do this, the Mac Mini stops sleeping well; the drives won't spin down, and "Safe Sleep" (using "pmset -a hibernatemode 1" or the "Deep Sleep" widget) stops working. Any ideas why? Only the RAID seems to cause the problem; I reformatted everything and tested each step of the setup (partitioning, Boot Camp, etc.) and only the final step (creating the RAID) caused the sleep issue.
[Before the backup mafia comes after me, I know that RAID isn't backup. That's why the second partition on the external drive is a bootable static backup, and a second 40GB external drive is used as a fail-safe backup of the critical user files. I use the RAID because it speeds up disk-limited operations like app startup, login, and boot, which is a big boost for the Mini, because its drive is slow.]
Output from "diskutil list", poorly formatted:
/dev/disk0
#: type name size identifier
0: GUIDpartitionscheme *93.2 GB disk0
1: EFI 200.0 MB disk0s1
2: Apple_RAID 84.0 GB disk0s2
3: Apple_Boot Boot OSX 128.0 MB disk0s3
4: Microsoft Basic Data 8.8 GB disk0s4
/dev/disk1
#: type name size identifier
0: Apple_HFS Macintosh HD *84.0 GB disk1
/dev/disk2
#: type name size identifier
0: GUIDpartitionscheme *232.9 GB disk2
1: EFI 200.0 MB disk2s1
2: Apple_RAID 84.1 GB disk2s2
3: Apple_Boot Boot OSX 128.0 MB disk2s3
4: Apple_HFS Backup 84.1 GB disk2s4
5: Apple_HFS Aux Storage 64.2 GB disk2s5

Answer 1

Nope, I never fixed the problem.  I bought a new monitor because I couldn't deal with the no-sleep issue.  That was after trying both an HDMI-to-DVI adapter and a Mini DisplayPort-to-DVI adapter, to no avail.  My replacement monitor allows me to select between "TV" or "PC" modes, so the display sleeps properly.  My Windows 7 partition still does all kinds of funky overscan glitches when I change out of the native resolution, but beta AMD drivers seem to have cured that problem.
I wish the industry would leave computer protocols for computers and keep the consumer A/V stuff separate.  Between that and the awful television aspect ratios they're forcing on us, it's getting annoying.  (That was one of the things I loved about the Hanns.G 28" monitor -- those extra 120 height pixels make a difference!)