Extends the volume or partition with focus, and its file system, into free (unallocated) space on a disk. Syntax: EXTEND ...

    Extends the volume or partition with focus, and its file system, into free
    (unallocated) space on a disk.

Syntax:  EXTEND [SIZE=] [DISK=] [NOERR]
        EXTEND FILESYSTEM [NOERR]

    SIZE=    Specifies the amount of space in megabytes (MB) to add to the
                current volume or partition. If no size is given, all of the
                contiguous free space that is available on the disk is used.

    DISK=    Specifies the disk on which the volume or partition is
                extended. If no disk is specified, the volume or partition is
                extended on the current disk.

    FILESYSTEM  Extends the file system of the volume with focus to cover 
                the entire volume. For use only on volumes where the file
                system was not extended with the volume.

    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.

    On basic disks, the free space must be on the same disk as the volume or
    partition with focus. The free space must also immediately follow the 
    volume or partition with focus (start at the next sector offset).

    On dynamic disks with simple or spanned volumes, a volume can be extended
    to any free space on any dynamic disk. Using this command, you can convert
    a simple dynamic volume into a spanned dynamic volume. Mirrored, RAID-5 and 
    striped volumes cannot be extended.

    If the partition was previously formatted with the NTFS file system, the
    file system is automatically extended to fill the larger partition. No data
    loss occurs. If the partition was previously formatted with a different
    file system than NTFS, the command fails with no change to the partition.
    If the partition was not previously formatted with a file system, the
    partition will still be extended.

    A volume or partition must be selected for this operation to succeed.

Example:

    EXTEND SIZE=500 DISK=3
    EXTEND FILESYSTEM