Breaks the mirrored volume with focus into two simple volumes. Syntax: BREAK DISK= NOKEEP NOERR DISK= Specifies a disk that ...

    Breaks the mirrored volume with focus into two simple volumes.

Syntax:  BREAK DISK= [NOKEEP] [NOERR]

    DISK=    Specifies a disk that contains one copy of the mirror 
                volume. When the command has completed, this disk is 
                given focus, and the new volume created on this disk 
                using the mirror volume extents does not retain any 
                drive letters, volume GUID pathnames or mounted folder 
                paths that had been associated with the mirror volume. 
                If the mirror volume on the specified disk is used as a
                system or boot partition, the command fails.

    NOKEEP      Specifies that only one copy of the mirror volume is 
                retained; the mirror volume extents on disk  are converted
                to free  space. Neither the remaining copy of the mirror 
                volume, nor the free space on disk  receives the focus.

    NOERR       For scripting only. When an error is encountered, DiskPart
                continues to process commands as if the error did not occur.
                Without the NOERR parameter, an error causes DiskPart to exit
                with an error code.

    Applies to dynamic disks only. Breaks the mirrored volume with focus into
    two simple volumes. One simple volume retains the drive letter, volume 
    GUID pathnames or mounted folder paths that had been associated with 
    the mirror volume. The other simple volume receives the focus so you 
    can assign it a new drive letter (it will automatically be assigned a 
    volume GUID pathname).

    By default, the contents of both copies of the mirror are retained. Each
    copy becomes a simple volume. By using the NOKEEP parameter, you retain
    only one copy of the mirror volume as a simple volume, and the other copy
    is converted to free space. Neither volume receives the focus.

    A mirror volume must be selected for this operation to succeed.

Example:

    BREAK DISK=2