VERITAS Volume Manager 3.1 Administrator's Guide

Volume Manager Operations
Online Relayout
Chapter 3 101
A striped mirror plex is a striped plex on top of a mirrored volume,
resulting in a single plex that has both mirroring and striping. This
combination forms a plex called a striped-mirror plex. A concatenated
plex can be created in the same way. Online Relayout supports
transformations to and from striped-mirror and concatenated-mirror
plexes.
NOTE Changing the number of mirrors during a transformation is not
currently supported.
Transformation Characteristics
Transformation of data from one layout to another involves
rearrangement of data in the existing layout to the new layout.
During the transformation, Online Relayout retains data redundancy by
mirroring any temporary space used.
Read/write access to data is not interrupted during the transformation.
Data is not corrupted if the system fails during a transformation. The
transformation continues after the system is restored and read/write
access is maintained.
You can reverse the layout transformation process at any time, but the
data may not be returned to the exact previous storage location. Any
existing transformation in the volume should be stopped before doing a
reversal.
You can determine the transformation direction by using the
vxrelayout status command.
These transformations eliminate I/O failures as long as there is sufficient
redundancy to move the data.
Transformations and Volume Length
Some layout transformations can cause the volume length to increase or
decrease. If the layout transformation causes the volume length to
increase or decrease, Online Relayout uses the vxresize command to
shrink or grow a file system.
Sparse plexes are not transformed by Online Relayout, and no plex can