HP Serviceguard Version A.11.18 Release Notes, September 2008

(Network-Attached Storage) context to denote a virtual entity derived from one or
more physical disks.
As of Serviceguard A.11.18 you can configure a LUN as the cluster lock.
Keep the following points in mind when choosing a device for a lock LUN:
• All the cluster nodes must be physically connected to the lock LUN.
• Connections between the nodes and the lock LUN must be Fibre Channel only;
parallel SCSI is not supported.
• All existing data on the LUN will be destroyed when you configure it as a lock
LUN.
• A lock LUN cannot also be used in an LVM physical volume or VxVM or CVM
disk group.
• A lock LUN cannot be shared by more than one cluster.
• A lock LUN cannot be used in a dual-lock configuration.
• You do not need to back up the lock LUN data, and in fact there is no way to do
so.
• A lock LUN needs only a small amount of storage, about 100 KB.
For more information, see “Setting Up a Lock LUN” in Chapter 5 of Managing
Serviceguard and the cmdisklock (1m) manpage.
About Device Special Files (DSFs)
HP-UX releases up to and including 11i v2 use a naming convention for device files
that encodes their hardware path. For example, a device file named /dev/dsk/
c3t15d0 would indicate SCSI controller instance 3, SCSI target 15, and SCSI LUN 0.
HP-UX 11i v3 introduces a new nomenclature for device files, known as agile addressing
(sometimes also called persistent LUN binding).
Under the agile addressing convention, the hardware path name is no longer encoded
in a storage device’s name; instead, each device file name reflects a unique instance
number, for example /dev/[r]disk/disk3, that does not need to change when the
hardware path does.
Agile addressing is the default on new 11i v3 installations, but the I/O subsystem still
recognizes pre-11i v3 device files, which as of 11i v3 are referred to as legacy device
files. Device files using the new nomenclature are called persistent device files,
When you upgrade to HP-UX 11i v3, a set of new, persistent device files is created, but
the existing, legacy device files are left intact and by default will continue to be used
by HP-UX and Serviceguard.
This means that you are not required to migrate to agile addressing when you upgrade
to 11i v3, though you should seriously consider its advantages (see the white paper
The Next Generation Mass Storage Stack under Network and Systems Management
-> Storage Area Management at docs.hp.com). Migration involves modifying
46 Serviceguard Version A.11.18 Release Notes