VERITAS Volume Manager 5.0 Migration Guide (September 2006)

8 VxVM and LVM
Introducing Veritas Volume Manager
ServiceGuard products. Refer to the Release Notes for details about the required
version number, as well as the availability of specific features in your release.
Notable features of VxVM
The Veritas Volume Manager provides many features, some of which are not available
with LVM or MirrorDisk/UX. Notable VxVM features are described in the list below. See
the Release Notes for a more detailed list of features available in each Veritas Volume
Manager product. See the other Veritas Volume Manager documents 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 Enterprise Administrator (VEA), which is a JAVA-based GUI for
VxVM.
■ Dynamic Multipathing (DMP) for active-passive devices, such as 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.
■ 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 paths such as xp256, EMC Symmetrix disk
array, and other OEM array devices.
■ Multiple mirroring with up to 32 mirror copies of a volume’s address space.
■ Mirrored stripes (RAID-0 + RAID-1) and striped mirrors (RAID-1 + RAID-0)
combine the benefits of striping to improve performance by spreading data