VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Volume Layouts in VxVM

30 VERITAS Volume Manager Administrator’s Guide

Layered Volumes

A layered volume is a virtual VERITAS Volume Manager object that is built on top of other

volumes. The layered volume structure tolerates failure better and has greater

redundancy than the standard volume structure. For example, in a striped-mirror layered

volume, each mirror (plex) covers a smaller area of storage space, so recovery is quicker

than with a standard mirrored volume.

The ﬁgure, “Example of a Striped-Mirror Layered Volume,” illustrates the structure of a

typical layered volume. It shows subdisks with two columns, built on underlying

volumes with each volume internally mirrored. The volume and striped plex in the

“Managed by User” area allow you to perform normal tasks in VxVM. User tasks can be

performed only on the top-level volume of a layered volume.

Underlying volumes in the “Managed by VxVM” area are used exclusively by VxVM and

are not designed for user manipulation. You cannot detach a layered volume or perform

any other operation on the underlying volumes by manipulating the internal structure.

You canperform allnecessary operations in the“Managed by User” area that includesthe

top-level volume and striped plex (for example, resizing the volume, changing the

column width, or adding a column).

Example of a Striped-Mirror Layered Volume

Mirrored

Plexes

VM Disks

Underlying

Subdisks Striped Plex Volume

vol01-01

vol01

vol01-01

vop01

vop02

Concatenated

Managed by User

Managed by VxVM

Column 1

Column 0

Subdisks on

disk04-01

disk05-01

disk06-01