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Commands Reference, Volume 1

chlvcopy Command


Marks or unmarks mirror copy as a split mirror.


chlvcopy-f ] {  -B  [  -s ] } | {  -b  [  -c copy ] [  -f ] [  -P ] [  -l newlvname ] [  -w ] } LV name



  1. To use this command, you must either have root user authority or be a member of the system group.
  2. If persistence is used either by using the -P flag or by creating a child backup logical volume device by using the -l flag, it will cause the volume group to be usable only on AIX 4.3.2 or later. This is true even after removal of split mirror copy designation of the parent logical volume and the child backup logical volumes.
  3. For chlvcopy to be successful in a concurrent volume group environment, all the concurrent nodes must be at AIX 4.3.2 or later.

All partitions of a logical volume must be fresh before chlvcopy can mark a mirror copy as a split mirror. Only one copy may be designated as an online split mirror copy.

Although the chlvcopy command can mark online split mirror copies on logical volumes that are open (including logical volumes containing mounted file systems), this is not recommended unless the application is at a known state at the time the copy is marked as a split mirror. The split mirror copy is internally consistent at the time the chlvcopy command is run, but consistency is lost between the logical volume and the split mirror copy if the logical volume is accessed by multiple processes simultaneously and the application is not at a known state. When marking an open logical volume, data may be lost or corrupted. Logical volumes should be closed before marking online split mirror copies in order to avoid a potential corruption window.

If the persistence flag is not set to prevent the loss of backup data, the volume group should be set to not automatically varyon and the -n flag should be used with varyonvg to prevent stale partitions from being resynced. If the persistence flag (-P) is set, the following applies: In the event of a crash while an online split mirror copy exists (or multiples exist), the existence of copies is retained when the system is rebooted.


-b Marks a mirror copy as a split mirror copy.
-c copy Mirror copy to mark as split mirror copy. The allowed values of copy are 1, 2, or 3. If this option is not specified the default for copy is the last mirror copy of the logical volume.
-B Unmarks a mirror as split mirror copy. It will also attempt to remove the child backup logical volume, if one was created with the -l option.
-f Forces split mirror copy even if there are stale partitions. If used with the -B option, the child backup logical volume if one was created with the -l option, will be removed with the force option.
-l newlvname New name of the backup logical volume. Specifying the -l flag also sets the persistence option, allowing applications to access split mirror copy via newlvname.
-P Maintains information about the existence of an online split mirror copy across a reboot and also allows other nodes (in a concurrent mode environment) to be aware of the existence of the online split mirror copy.
-s Starts a background syncvg for the logical volume.
-w Allows split mirror copy to be writable (default is to create the split mirror copy as READ ONLY).
LV name Logical volume to act on.

Related Information

The readlvcopy and chfs commands.

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