Adding a copy of a logical volume
The mklvcopy command is used to add copies (mirroring) to a logical volume that has
none or to increase the copies from two or three. Specify the logical volume to change
and the desired total number of copies. This only succeeds if there are enough physical
partitions to satisfy the requirements on the physical volumes that are specified to be
used (that is, if all copies are to be on different physical volumes).
Once a logical volume has been created, striping cannot be imposed or removed.
Synchronizing a mirrored logical volume
Also, in order for the copies to match, the logical volume has to be synchronized using
the syncvg command. This can be done with the -k option when the copy is originally
started. It can be done later using the syncvg command