Operating system-based RAID cannot easily be used to protect the boot
process and is generally impractical on desktop version of Windows (as
described above). Hardware RAID controllers are expensive. To fill this gap
cheap "RAID controllers" were introduced that do not contain a RAID
controller chip, but simply a standard disk controller chip with special
firmware and drivers. During early stage boot up the RAID is implemented by
the firmware; when a protected-mode operating system kernel such as Linux
or a modern version of Microsoft Windows is loaded the drivers take over.
These controllers are described by their manufacturers as RAID controllers,
and it is rarely made clear to purchasers that the burden of RAID
processing is borne by the host computer's central processing unit, not the
RAID controller itself, thus introducing the aforementioned CPU overhead.
Before their introduction, a "RAID controller" implied that the controller
did the processing, and the new type has become known in technically
knowledgeable circles as "fake RAID" even though the RAID itself is
Example of true RAID cards supported by EZblue:
Adaptec/ AAR-2610SA 6 Port 64MB SATA RAID card.