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Product: Volume Manager Guides   
Manual: Volume Manager 4.1 Administrator's Guide   

Adding a Mirror to a Volume

A mirror can be added to an existing volume with the vxassist command, as follows:


vxassist [-b] [-g diskgroup] mirror volume
Note   Note    If specified, the -b option makes synchronizing the new mirror a background task.

For example, to create a mirror of the volume voltest in the disk group, mydg, use the following command:


vxassist -b -g mydg mirror voltest

Another way to mirror an existing volume is by first creating a plex, and then attaching it to a volume, using the following commands:


vxmake [-g diskgroup] plex plex sd=subdisk ... 
vxplex [-g diskgroup] att volume plex  

Mirroring All Volumes

To mirror all volumes in a disk group to available disk space, use the following command:


/etc/vx/bin/vxmirror -g diskgroup -a

To configure VxVM to create mirrored volumes by default, use the following command:


/etc/vx/bin/vxmirror -d yes

If you make this change, you can still make unmirrored volumes by specifying nmirror=1 as an attribute to the vxassist command. For example, to create an unmirrored 20-gigabyte volume named nomirror in the disk group, mydg, use the following command:


vxassist -g mydg make nomirror 20g nmirror=1

Mirroring Volumes on a VM Disk

Mirroring volumes on a VM disk gives you one or more copies of your volumes in another disk location. By creating mirror copies of your volumes, you protect your system against loss of data in case of a disk failure.


Note   Note    This task only mirrors concatenated volumes. Volumes that are already mirrored or that contain subdisks that reside on multiple disks are ignored.

To mirror volumes on a disk, make sure that the target disk has an equal or greater amount of space as the originating disk and then do the following:

  1. Select menu item 5 (Mirror volumes on a disk) from the vxdiskadm main menu.
  2. At the following prompt, enter the disk name of the disk that you wish to mirror:
    Mirror volumes on a disk 
    Menu: VolumeManager/Disk/Mirror 

    This operation can be used to mirror volumes on a disk. These
    volumes can be mirrored onto another disk or onto any 
    available disk space. Volumes will not be mirrored if they are
    already mirrored. Also, volumes that are comprised of more than
    one subdisk will not be mirrored. 

    Enter disk name [<disk>,list,q,?] mydg02 
  3. At the following prompt, enter the target disk name (this disk must be the same size or larger than the originating disk):
    You can choose to mirror volumes from disk mydg02 onto any
    available disk space, or you can choose to mirror onto a
    specific disk. To mirror to a specific disk, select the name of
    that disk. To mirror to any available disk space, select "any". 
    Enter destination disk [<disk>,list,q,?] (default: any) mydg01
  4. At the following prompt, press Return to make the mirror:
    The requested operation is to mirror all volumes on disk mydg02
    in disk group mydg onto available disk space on disk mydg01.
    VxVM NOTICE V-5-2-229 This operation can take a long time to complete.
    Continue with operation? [y,n,q,?] (default: y)

    The vxdiskadm program displays the status of the mirroring operation, as follows:


    VxVM vxmirror INFO V-5-2-22 Mirror volume voltest-bk00 ... 
    VxVM INFO V-5-2-674 Mirroring of disk mydg01 is complete. 
  5. At the following prompt, indicate whether you want to mirror volumes on another disk (y) or return to the vxdiskadm main menu (n):
    Mirror volumes on another disk? [y,n,q,?] (default: n) 
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Product: Volume Manager Guides  
Manual: Volume Manager 4.1 Administrator's Guide  
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