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Commands Reference, Volume 5

unmirrorvg Command


Removes the mirrors that exist on volume groups or specified disks. This command only applies to AIX 4.2.1 or later.


unmirrorvg-c Copies ] VolumeGroupPhysicalVolume .. . ]


The unmirrorvg command unmirrors all the logical volumes detected on a given volume group. This same functionality may also be accomplished manually if you execute the rmlvcopy command for each individual logical volume in a volume group.

By default, unmirrorvg will pick the set of mirrors to remove from a mirrored volume group. If you wish to control which drives no longer are to contain mirrors, you must include the list of disks in the input parameters, PhysicalVolume.

When the PhysicalVolume parameter is listed in the command, this indicates that only the mirrors that exist on this disk should be unmirrored. Mirrors that exist on other drives in the volume group, but not listed in a user-provided disk list are left alone and remain mirrored.

Note: If a logical volume copy spans more than one disk, the portion of the logical volume copy that resides on a disk not listed by the user is also removed.

When unmirrorvg is executed, the default COPIES value for each logical volume becomes 1. If you wish to convert your volume group from triply mirrored to doubly mirrored, use the -c option.

Note: To use this command, you must either have root user authority or be a member of the system group.

Attention: The unmirrorvg command may take a significant amount of time to complete because of complex error checking and the number of logical volumes to unmirror in a volume group.

Y ou can use the System Management Interface Tool (SMIT) to run this command. To use SMIT, enter:

smit unmirrorvg


-c Copies Specifies the minimum number of copies that each logical volume must have after the unmirrorvg command has finished executing. If you do not want all logical volumes to have the same number of copies, then reduce the mirrors manually with the rmlvcopy command. If this option is not used, the copies will default to 1.


  1. To unmirror a triply mirrored volume group and leave two copies, enter:

    unmirrorvg -c 2 workvg

    The logical partitions in the logical volumes held on workvg now have 2 copies.

  2. To get default unmirroring of rootvg, enter:

    unmirrorvg rootvg

    rootvg now has only 1 copy.

  3. To replace a bad disk drive in a mirrored volume group, enter:

    unmirrorvg workvg hdisk7
    reducevg workvg hdisk7
    rmdev -l hdisk7 -d
    replace the disk drive, let the drive be renamed hdisk7
    extendvg workvg hdisk7
    mirrorvg workvg

    Note: By default in this example, mirrorvg will try to create 2 copies for logical volumes in workvg. It will try to create the new mirrors onto the replaced disk drive. However, if the original system had been triply mirrored, there may be no new mirrors created onto hdisk7, as other copies may already exist for the logical volumes. This follows the default behavior of unmirrorvg to reduce the mirror copy count to 1.


/usr/sbin Directory where the unmirrorvg command resides.

Related Information

The mklvcopy command, mirrorvg command, syncvg command, reducevg command, extendvg command.

The Logical Volume Storage Overview in AIX 5L Version 5.1 System Management Concepts: Operating System and Devices.

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