VERITAS Volume Manager 3.1 Administrator's Guide

Volume Manager Operations
Creating Volumes
Chapter 3 91
Creating Volumes
Volumes are createdto take advantage of theVolume Manager concept of
virtual disks. Once a volume exists, a file system can be placed on the
volume to organize the disk space with files and directories. Also,
applications such as databases can be used to organize data on volumes.
Create volumes using either a basic or advanced approach, as described
below:
• Basic—The basic approach takes information about what you want to
accomplish and then performs the necessary underlying tasks. This
approach requires only minimal input from you, but also permits
more detailed specifications. Basic operations are performed
primarily through the vxassist command.
• Manual—The advanced approach consists of a number of commands
that typically require you to specify detailed input. These commands
use a “building block” approach that requires you to have a detailed
knowledge of the underlying structure and components to manually
perform the commands necessary to accomplish a certain task.
Advanced operations are performed through several Volume Manager
commands.
The creation of a volume involves the creation of plex and subdisk
components. With the basic approach to volume creation, you indicate
the desired volume characteristics and the underlying plexes and
subdisks are created automatically.
Volumes can be created with various layout types:
• Concatenated—A volume whose subdisks are arranged both
sequentially and contiguously within a plex. Concatenation allows a
volume to be created from multiple regions of one or more disks if
there is not enough space for an entire volume on a single region of a
disk.
• Striped—A volume with data spread evenly across multiple disks.
Stripes are equal-sized fragments that are allocated alternately and
evenly to the subdisks of a single plex. There must be at least two
subdisks in a striped plex, each of which must exist on a different
disk. Throughput increases with the number of disks across which a
plex is striped. Striping helps to balance I/O load in cases where high