VERITAS Volume Manager 3.5 User's Guide - VERITAS Enterprise Administrator (June 2002)

VxVM Volumes
78 VERITAS Volume Manager User’s Guide - VEA
VxVM Volumes
VxVM uses logical volumes to organize and manage disk space. A volume is made up of
portions of one or more physical disks, so it does not have the physical limitations of a
physical disk.
A volume can provide greater capacity and better availability and performance than a
single physical disk. A volume can be extended (grown) across multiple disks to increase
capacity, mirrored (copied) on another disk to provide data redundancy, and/or striped
across multiple disks to improve I/O performance.
You can use VxVM to create the following types of volumes:
◆ Concatenated Volume
A concatenated volume is made up of one or more disk regions that are linked
together (concatenated) ina linearfashion. Aconcatenated volume can consist of disk
regions on multiple disks; a concatenated volume that extends across two or more
disks is also known as a spanned volume.
Note Data in this type of volume cannot be recovered if the underlying disk fails.
However, a concatenated volume can be mirrored (copied) onto other disks to
protect its data against disk failure.
◆ Striped Volume
Striped volume data is interleaved (striped) across two or more physical disks.
Striped volume data is spread across the disks alternately and evenly in small,
equal-sized portions of data called stripe units. Striping improves performance.
Note Data in this type of volume cannot be recovered if one of the underlying disks fails.
However, a striped volume can be mirrored (copied) onto other disks to protect its
data against disk failure.
◆ RAID-5 Volume
RAID-5 volume data is interleaved (striped) across three or more physical disks.
Within each stripe across the set of disks, the data on one of the disks is parity data. If
one of the physical disks fails, the parity data can be used to reconstruct and recover
the lost data.
Note RAID-5 volumes cannot be mirrored.