In disk mirroring, partitions on two drives store identical information so that one is the mirror of the other. All data written to the partition on the primary disk is also written to the mirror, or secondary, partition. If one disk fails, the system is able to use the data from the other disk.
Mirrors are file system independent.
Any partition using a file system that Windows NT recognizes or that is blank can be used to create a mirror. Mirrors are not dependent on disk geometry. The only requirement is that free disk space used to place the mirror on be equal to or greater than the size of the primary partition. Primary and mirror partitions must be on separate hard disk drives. They cannot be on the same physical hard disk drive.