VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Volume Layouts in VxVM
16 VERITAS Volume Manager Administrator’s Guide
The figure, “Example of Spanning” on page 16 shows data spread over two subdisks in a
spanned plex. In the figure, “Example of Spanning,” the first six blocks of data (B1
through B6) use most of the space onthe disk to which VM disk disk01 is assigned. This
requires space only on subdisk disk01-01 on disk01. However, the last two blocks of
data, B7 and B8, use only a portion of the space on the disk to which VM disk disk02 is
assigned.
The remaining free space on VM disk disk02 can be put to other uses. In this example,
subdisks disk02-02 and disk02-03 are available for other disk management tasks.
Example of Spanning
Caution Spanning a plex across multiple disks increases the chance that a disk failure
results in failure of the assigned volume. Use mirroring or RAID-5 (both
described later) to reduce the risk that a single disk failure results in a volume
failure.
See “Creating a Volume on Any Disk” on page 165 for information on how to create a
concatenated volume that may span several disks.
B = Block of Data
VM Disks
Physical disks
Data in
disk01-01
Data in
disk02-01
Plex
disk01
disk01-01
disk02
disk02-01
disk02-02
disk02-03
B2
B1
B3
B4
B5
B6
B7
B8
devname1
devname2
disk02-01
disk02-03
disk01-01
disk02-02