Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

■ The usual restrictions apply for the minimum number of physical disks that

are required to create the destination layout. For example, mirrored volumes

require at least as many disks as mirrors, striped and RAID-5 volumes require

at least as many disks as columns, and striped-mirror volumes require at least

as many disks as columns multiplied by mirrors.

■ To be eligible for layout transformation, the plexes in a mirrored volume must

have identical stripe widths and numbers of columns. Relayout is not possible

unless you make the layouts of the individual plexes identical.

■ Online relayout cannot transform sparse plexes, nor can it make any plex

sparse. (A sparse plex is a plex that is not the same size as the volume, or that

has regions that are not mapped to any subdisk.)

■ The number of mirrors in a mirrored volume cannot be changed using relayout.

Use alternative commands instead.

■ 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. Before you reverse a

transformation that is in process, you must stop it.

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 command

to shrink or grow a file system.

See “Resizing a volume” on page 330.

Understanding Veritas Volume Manager

Online relayout