VERITAS Volume Manager 4.1 Administrator's Guide

Understanding VERITAS Volume Manager
Volume Layouts in VxVM
Chapter 1 33
units are used for each column. For RAID-5, the default stripe unit size is
16 kilobytes. See “Striping (RAID-0)” on page 22 for further information
about stripe units.
Figure 1-23 Volume ManagerRAID-5 Array
NOTE Mirroring of RAID-5 volumes is not currently supported.
See “Creating a RAID-5 Volume” on page 252 for information on how to
create a RAID-5 volume.
Left-Symmetric Layout
There are several layouts for data and parity that can be used in the
setup of a RAID-5 array. The implementation of RAID-5 in VxVM uses a
left-symmetric layout. This provides optimal performance for both
random I/O operations and large sequential I/O operations. However, the
layout selection is not as critical for performance as are the number of
columns and the stripe unit size.
Column 0 Column 1 Column 2 Column 3
SD
SD
SD
SD SD
SD
SD
SD
SD = Subdisk
Stripe 1
Stripe 2