Managing Serviceguard A.11.20, March 2013

• GIDs are the same on all nodes.
• Applications in the system area are the same on all nodes.
• System time is consistent across the cluster.
• Files that could be used by more than one node, such as files in the /usr directory, must be
the same on all nodes.
About Cluster-wide Device Special Files (cDSFs)
Under agile addressing on HP-UX 11i v3, each device has a unique identifier as seen from a given
host; this identifier is reflected in the name of the Device Special File (DSF). See “About Device
File Names (Device Special Files)” (page 81) for more information.
Because DSF names may be duplicated between one host and other, it is possible for different
storage devices to have the same name on different nodes in a cluster, and for the same piece of
storage to be addressed by different names. Cluster-wide device files (cDSFs), available as of the
September 2010 HP-UX Fusion Release, ensure that each storage device used by the cluster has
a unique device file name.
IMPORTANT: Check the latest version of the release notes (at the address given in the preface
to this manual) for information about Serviceguard support for cDSFs.
HP recommends that you use cDSFs for the storage devices in the cluster because this makes it
simpler to deploy and maintain a cluster, and removes a potential source of configuration errors.
See “Creating Cluster-wide Device Special Files (cDSFs)” (page 164) for instructions.
Points To Note
• cDSFs can be created for any group of nodes that you specify, provided that Serviceguard
A.11.20 is installed on each node.
Normally, the group should comprise the entire cluster.
• cDSFs apply only to shared storage; they will not be generated for local storage, such as root,
boot, and swap devices.
• Once you have created cDSFs for the cluster, HP-UX automatically creates new cDSFs when
you add shared storage.
• HP recommends that you do not mix cDSFs with persistent (or legacy) DSFs in a volume group.
You cannot use cmpreparestg (1m) on a volume group in which they are mixed.
See “About Easy Deployment” (page 110) for more information about cmpreparestg.
Where cDSFs Reside
cDSFs reside in two new HP-UX directories, /dev/cdisk for cluster-wide block devicefiles and
/dev/rcdisk for cluster-wide character devicefiles. Persistent DSFs that are not cDSFs continue
to reside in /dev/disk and /dev/rdisk, and legacy DSFs (DSFs using the naming convention
that was standard before HP–UX 11i v3) in /dev/dsk and /dev/rdsk. It is possible that a
storage device on an 11i v3 system could be addressed by DSFs of all three types of device —
but if you are using cDSFs, you should ensure that you use them exclusively as far as possible.
NOTE: Software that assumes DSFs reside only in /dev/disk and /dev/rdisk will not find
cDSFs and may not work properly as a result; as of the date of this manual, this was true of the
Veritas Volume Manager, VxVM.
Cluster Configuration Planning 109