Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

28 Understanding Veritas Volume Manager
How VxVM handles storage management
Subdisks
A subdisk is a set of contiguous disk blocks. A block is a unit of space on the disk. VxVM
allocates disk space using subdisks. A VM disk can be divided into one or more subdisks.
Each subdisk represents a specific portion of a VM disk, which is mapped to a specific
region of a physical disk.
The default name for a VM disk is diskgroup## and the default name for a subdisk is
diskgroup##-##, where diskgroup is the name of the disk group to which the disk
belongs (see “Disk groups” on page 26).
In Figure 1-7, disk01-01 is the name of the first subdisk on the VM disk named
disk01.
Figure 1-7 Subdisk example
A VM disk can contain multiple subdisks, but subdisks cannot overlap or share the same
portions of a VM disk. Figure 1-8 shows a VM disk with three subdisks. (The VM disk is
assigned to one physical disk.)
Subdisk
VM disk with one subdisk
disk01-01
disk01
disk01-01