A mirrored volume consists of at least two subdisks of identical sizes that are located on separate disks. Each time a file system or application writes to the volume, Storage Foundation for Windows transparently writes the same data to each of the volume's subdisks. With Storage Foundation for Windows, you can have up to 32 mirrors for all volume types except for RAID-5.

Add Mirror: The primary purpose of mirroring is to provide fault tolerance; however, mirrored volumes can also improve I/O performance for most I/O-intensive applications, which make substantially more read requests than writes. With mirrored volumes, write requests may take longer than with non-mirrored volumes, but the effects are typically minor.

Break Mirror: An important use of mirroring is the practice of breaking off a third mirror that can be used as a snapshot for backup or for other activities, such as uploading or updating data warehouses or performing application testing.

Remove Mirror: Removing a mirror from a volume "removes" or destroys the data from the selected mirror and leaves the other mirror or mirrors intact. After you remove a mirror, the disk space that the removed mirror uses becomes unallocated free space.

You use the Mirror Wizard to complete these tasks. The end of the Mirror Wizard displays a summary of the details of the operation.