afaik did the Raidcontroller on PE2850 not beeping. It's normal the boot stops at raidcontroller. Normally your server is running. If hdd would fail hotspare will start to rebuild.

If you have installed OpenManage and would monitor you system you would getting error message.

If you want a test, don't do it with the server off, but yank a drive while the system is running. When we got our PV660f and our 6450, I set up the server initially, then I just yanked a drive on the RAID 1 (onboard), put it back in and then did the same for the RAID 5 on the 660f. The system barely hiccuped, and the alarm went off, but the sytem just kept chugging away. When I put the disks back in the system went on it's merry way rebuilding them.

As for your system not wanting to boot, I can only think because it was in a power off state it didn't know what the correct configuration was supposed to be and was wanting some sort of user input in the setup.

Reason I say that is the PERC cards store the configuration in both NVRAM and on each drive. So if the card fails, it can rebuild from the drive configuration.