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

Chapter 1, Understanding VERITAS Volume Manager

Volume Layouts in VxVM

Connection Between Objects in VxVM

Volume Layouts in VxVM

A VxVM virtual device is deﬁned by a volume. A volume has a layout deﬁned by the

association of a volume to one or more plexes, each of which map to subdisks. The

volume presents a virtual device interface that is exposed to other applications for data

access.These logicalbuilding blocksre-mapthe volume addressspace throughwhich I/O

is re-directed at run-time.

Different volume layoutseach providedifferent levels of storageservice. Avolume layout

can be conﬁgured and reconﬁgured to match particular levels of desired storage service.

Implementation of Non-Layered Volumes

In a non-layered volume, a subdisk is restricted to mapping directly to a VM disk. This

allows the subdisk to deﬁne a contiguous extent of storage space backed by the public

region of a VM disk. When active, the VM disk is directly associated with an underlying

physical disk. The combination of a volume layout and the physical disks therefore

determines the storage service available from a given virtual device.

VM Disk

Physical Disk

disk01

vol01-01

disk01-01

disk01-02

vol01

disk01-01

disk01-02

Disk Group

VM Disk

disk02

vol02-01

disk02-01

vol02

disk02-01

Physical Disk

Volume

Plex

Subdisk

Subdisks

devname1

devname2