VERITAS Volume Manager 3.1 Storage Administrator Administrator's Guide

Volume Tasks
Creating a Volume
Chapter 4 149
Creating a Volume
The Volume Manager 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 the Volume Manager Storage Administrator 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) in a linear fashion. A concatenated
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 that the data in this type of volume cannot be recovered if the
underlying disk fails. However, a concatenated volume can be
mirrored (copied) onto another disk(s) to protect its data against disk
failure.
• Striped Volume
A striped volume’s data is interleaved (striped) across two or more
physical disks. A striped volume’s data is spread across the disks
alternately and evenly in small, equal-sized portions of data called
stripe units . Striping improves performance.
Note that the 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 another disk(s) to protect its data against disk failure.
• RAID-5 Volume
A RAID-5 volume’s 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.