VERITAS Volume Manager 4.1 Administrator's Guide

Understanding VERITAS Volume Manager
Online Relayout
Chapter 1 43
• Online relayout involving RAID-5 volumes is not supported for
shareable disk groups in a cluster environment.
• Online relayout cannot transform sparse plexes, nor can it make any
plex sparse. (A sparse plex is not the same size as the volume, or has
regions that are not mapped to any subdisk.) .
• The number of mirrors in a mirrored volume cannot be changed
using relayout. .
• Only one relayout may be applied to a volume at a time.
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 and 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 both read and
write access are 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 must be stopped before doing a
reversal.
You can determine the transformation direction by using the vxrelayout
status volume command.
These transformations are protected against I/O failures if there is
sufficient redundancy and space to move the data.
Transformations and Volume Length
Some layout transformations can cause the volume length to increase or
decrease. If either of these conditions occurs, online relayout uses the
vxresize(1M) command to shrink or grow a file system as described in
“Resizing a Volume” on page 288.