I have a Dell PowerEdge T710 under my feet at this very moment, with RedHat Enterprise Server 5.3.

I have 6 1TB disks and two 500GB. parted reports two devices, one 500 GB and the other 4 TB. So I assume the RAID has been setup as mirror for two disks, and I assume as RAID 5 the remaining ones. I say "I assume" because it does not make sense. Having 6 disks in RAID 5, I should obtain a total space of 5 TB, not 4TB. It's not even RAID 10: I would end up with a 3 TB unit.

How can I check and eventually modify the RAID array definition? In the Fujitsu Siemens I played with some time ago, at boot I had the chance to enter the controller BIOS, but here I don't see a clear way to perform this operation.