Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Figure 1-11
Example of a volume with two plexes
Volume with two plexes
Plexes
vol06-01 vol06-02
vol06
vol06-01 vol06-02
disk01-01 disk02-01
Each plex of the mirror contains a complete copy of the volume data.
The volume vol06 has the following characteristics:
■ It contains two plexes named vol06-01 and vol06-02.
■ Each plex contains one subdisk.
■ Each subdisk is allocated from a different VM disk (disk01 and disk02).
See “Mirroring (RAID-1)” on page 41.
VxVM supports the concept of layered volumes in which subdisks can contain
volumes.
See “Layered volumes” on page 49.
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 one or
more subdisks. The volume presents a virtual device interface that is exposed to
other applications for data access. These logical building blocks re-map the volume
address space through which I/O is re-directed at run-time.
Different volume layouts provide different levels of availability and performance.
A volume layout can be configured and changed to provide the desired level of
service.
Non-layered volumes
In a non-layered volume, a subdisk maps 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
Understanding Veritas Volume Manager
Volume layouts in VxVM
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