Serviceguard Extension for RAC Version A.11.18 Release Notes, 3rd Edition, April 2008

/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 system and application configuration files and scripts
to use persistent device files and in some cases new commands and options; the process
is described in the white papers Migrating from HP-UX 11i v2 to HP-UX 11i v3 and LVM
Migration from Legacy to Agile Naming Model HP-UX 11i v3 at http://docs.hp.com.
If you cold-install HP-UX 11i v3, sets of both legacy and persistent device files are
automatically created. In this case, by default the installation process will configure
system devices such as the boot, root, swap, and dump devices to use persistent device
files. This means that system configuration files such as /etc/fstaband /etc/lvmtab
will contain references to persistent device files, but Serviceguard’s functioning will
not be affected by this.
CAUTION: You cannot migrate to the agile addressing scheme during a rolling upgrade
if you are using cluster lock disks as a tie-breaker, because that involves changing the
cluster configuration. But under certain conditions, you can migrate the cluster lock
device file names to the new scheme without bringing the cluster down. For the
requirements and a procedure, see the section “Updating the Cluster Lock
Configuration” in chapter 7 of the Managing Serviceguard Fifteenth Edition user’s guide.
NOTE: It is possible, though not a best practice, to use legacy DSFs on some nodes
after migrating to agile addressing on others; this allows you to migrate different nodes
at different times, if necessary.
For more information about agile addressing, see following documents at
http://docs.hp.com:
18 Serviceguard Extension for RAC Version A.11.18 Release Notes