HP Serviceguard Version A.11.20 Release Notes, April 2011

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 which you can find at http://www.hp.com/go/hpux-core-docs —> Overview:
The Next Generation Mass Storage Stack ). 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 paper LVM Migration from Legacy
to Agile Naming Model HP-UX 11i v3 at http://www.hp.com/go/hpux-core-docs.
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/fstab and /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 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 “Updating the Cluster Lock Configuration”
in Chapter 7 of Managing Serviceguard.
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://www.hp.com/
go/hpux-core-docs:
• the Logical Volume Management volume of the HP-UX System Administrator’s Guide
• the HP-UX 11i v3 Installation and Update Guide
• the following white papers:
The Next Generation Mass Storage Stack◦
◦ HP-UX 11i v3 Native Multi-Pathing for Mass Storage
◦ LVM Migration from Legacy to Agile Naming Model HP-UX 11i v3
See also the HP-UX 11i v3 intro(7) manpage.
32 Serviceguard Version A.11.20 Release Notes