Managing Serviceguard Fifteenth Edition, reprinted May 2008

Understanding Serviceguard Hardware Configurations
Redundant Disk Storage
Chapter 2 47
another node until the failing node is halted. Mirroring the root disk
allows the system to continue normal operation when a root disk failure
occurs.
Disk Arrays using RAID Levels and Multiple Data Paths
An alternate method of achieving protection for your data is to employ a
disk array with hardware RAID levels that provide data redundancy,
such as RAID Level 1 or RAID Level 5. The array provides data
redundancy for the disks. This protection needs to be combined with the
use of redundant host bus interfaces (SCSI or Fibre Channel) between
each node and the array.
The use of redundant interfaces protects against single points of failure
in the I/O channel, and RAID 1 or 5 configuration provides redundancy
for the storage media.
About Multipathing Multipathing is automatically configured in
HP-UX 11i v3 (this is often called native multipathing), or in some
cases can be configured with third-party software such as EMC
Powerpath.
NOTE 4.1 and later versions of Veritas Volume Manager (VxVM) and Dynamic
Multipathing (DMP) from Symantec are supported on HP-UX 11i v3, but
do not provide multipathing and load balancing; DMP acts as a
pass-through driver, allowing multipathing and load balancing to be
controlled by the HP-UX I/O subsystem instead.
For more information about multipathing in HP-UX 11i v3, see the white
paper HP-UX 11i v3 Native Multipathing for Mass Storage, and the
Logical Volume Management volume of the HP-UX System
Administrator’s Guide in the HP-UX 11i v3 Operating Environments
collection at http://docs.hp.com. See also “About Device File Names
(Device Special Files)” on page 112.
Monitoring LVM Disks Through Event Monitoring
Service
If you are using LVM, you can configure disk monitoring to detect a
failed mechanism by using the disk monitor capabilities of the EMS HA
Monitors, available as a separate product (B5736DA). Monitoring can be