Some history about Intel RAID under GNU/Linux (dmraid/mdadm)

Although RAID is supported under GNU/Linux since many years, it is not trivial either.
This article is about Intel RAID, but some information may apply to others kinds.

There is at least two tools allowing to manage RAID devices:

 - dmraid (Device-mapper RAID tool and library)
 - mdadm (controls Linux md devices - software RAID arrays)

Intel RAID can be regarded as pseudo-Hardware-based RAID or Software-based RAID, so the 2 tools can be used.
Anyway, mdadm is more commonly used with modern distribution (for instance Fedora switched from dmraid to mdraid since version 12).

Besides, if you ever have a problem after an OS upgrade, with an existing RAID that you manage with dmraid, you should use the kernel option "noiswmd" which will make the system use dmraid for Intel BIOS RAID instead of mdraid.