VERITAS Volume Manager 3.1 Migration Guide

VxVM and LVM
Introducing the VERITAS Volume Manager
Chapter 1 15
Manager documents (listed under “Related Documents” in the “Preface”)
for more details about using these features.
VERITAS Volume Manager includes the following features:
• Concatenation, the combining of discontiguous disk regions into
virtual devices.
• Spanning, concatenation across different physical media.
• Striping, distribution of storage mappings for a virtual device so that
multi-threaded accesses tend to cause even use of all physical media.
• The VERITAS Volume Manager Storage Administrator vmsa, a
JAVA-based GUI for VxVM. The Storage Administrator runs either
as an application or from a web browser.
• Dynamic Multipathing (DMP) for active-passive devices, such as
Model FC30 and FC60. DMP provides higher availability to data on
disks with multiple host-to-device pathways by providing a
disk/device path failover mechanism. In the event of a loss of one
connection to a disk, the system continues to access the data over the
other available connections to the disk.
• Free Space Management, providing simple goal-based allocation of
storage.
• Task Monitor, which tracks the progress of system recovery by
monitoring task creation, maintenance, and completion. The Task
Monitor allows you to pause, resume, and stop as desired to adjust
the impact on system performance.
The following VERITAS Volume Manager features require an additional
license (product B9116AA):
• Dynamic Multipathing (DMP) for active-active devices, such as HP
Surestore Disk Array xp256, HP Surestore Disk System FC10 and
other disk devices. DMP provides higher availability to data on disks
with multiple host-to-device pathways by providing a disk/device
path failover mechanism. In the event of a loss of one connection to a
disk, the system continues to access the data over the other available
connections to the disk. DMP also provides in some cases, improved
I/O performance from disks with multiple concurrently available
pathways by balancing the I/O load uniformly across multiple I/O
paths to the disk device. LVM supports path failover but does not
support I/O balancing. DMP support may be used with devices that
show improved performance when I/O is balanced across the multiple