The software based striped volume with parity (Raid-5) is not supported in Windows 7. However, Windows 7 do support hardware-based RAID using a hardware raid controller. This is by design according to Microsoft Technet Forums and considering that hardware-based RAID performs much better and has additional features, I tend to agree with Microsoft not to overload the system with additional cpu-intensive activity. What I don’t understand is why the option is there but not usable – it’s grayed out! Even, the Diskpart command line tool has a create volume raid option but if you try out, it returns – The command you selected is not available with this version of Windows.
Hardware RAID-5 offers failover protection and performance improvement. RAID-5 writes data in small blocks or stripes on three or more disks simultaneously. A stripe of data across all disks participating in the set consists of the actual data and parity information. Parity information is not stored on the same disk but distributed among the disks. In fact, RAID-5 is sometimes referred to as Striping with Distributed Parity.