Managing Serviceguard Eighteenth Edition, September 2010

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 206)
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, and you cannot use cmpreparestg (1m) on a volume group in
which they are mixed.
See “About Easy Deployment” (page 137) 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.
136 Planning and Documenting an HA Cluster