A mirrored volume, also known as a RAID-1 volume, is a fault-tolerant volume that duplicates data on two different physical disks. Mirrored volumes are supported on dynamic disks, and provide data redundancy by using two identical copies (mirrors) of the volume.
You cannot create mirrored volumes on computers that are running Windows XP Home Edition, Windows XP Professional, Windows 2000 Professional or Windows XP 64-Bit Edition.
Notice that the “Add Mirror” option is grayed out:
And if you try to add a new volume on the second disk, notice that there is no RAID1 – Mirror option: