Mirroring the boot and system volumes

Source  Win 2k3

Boot and system partitions. You can convert a basic disk containing the system or boot partitions to a dynamic disk. After the disk is converted, these partitions become simple system or boot volumes (after restarting the computer). You cannot mark an existing dynamic volume as active. You can convert a basic disk containing the boot partition (which contains the operating system) to a dynamic disk. After the disk is converted, the boot partition becomes a simple boot volume (after restarting the computer).

Mirroring the boot and system volumes. If you convert the disk containing the boot and system partitions to a dynamic disk, you can mirror the boot and system volumes onto another dynamic disk. Then, if the disk containing the boot and system volumes fails, you can start the computer from the disk containing the mirrors of these volumes. For more information, see Create and test a mirrored system or boot volume.

Converting dynamic disks to basic disks. After you convert a basic disk into a dynamic disk, you cannot change the dynamic volumes back to partitions. Instead, you must move or back up your data, delete all dynamic volumes on the disk and then convert the disk. For more information, see Change a dynamic disk back to a basic disk.