OpenVMS Cluster Systems - OpenVMS Systems - HP

Preparing a Shared Environment
5.5 Defining and Accessing Clusterwide Logical Names
5.5.3 Using Conditional Definitions for Startup Command Procedures
For clusterwide definitions in any startup command procedure that is common to
all cluster nodes, Compaq recommends that you use a conditional definition. For
example:
$ IF F$TRNLNM("CLUSTER_APPS") .EQS. "" THEN -
_$ DEFINE/TABLE=LNM$SYSCLUSTER/EXEC CLUSTER_APPS -
_$ $1$DKA500:[COMMON_APPS]
A conditional definition can prevent unpleasant surprises. For example, suppose
a system manager redefines a name that is also defined in SYSTARTUP_
VMS.COM but does not edit SYSTARTUP_VMS.COM because the new definition
is temporary. If a new node joins the cluster, the new node would initially
receive the new definition. However, when the new node executes SYSTARTUP_
VMS.COM, it will cause all the nodes in the cluster, including itself, to revert to
the original value.
If you include a conditional definition in SYLOGICALS.COM or
SYSECURITY.COM, specify the F$TRNLNM CASE argument as INTERLOCKED
to ensure that clusterwide logical names have been fully initialized before the
translation completes. An example of a conditional definition with the argument
specified follows:
$ IF F$TRNLNM("CLUSTER_APPS",,,,"INTERLOCKED") .EQS. "" THEN -
_$ DEFINE/TABLE=LNM$SYSCLUSTER/EXEC CLUSTER_APPS -
_$ $1$DKA500:[COMMON_APPS]
Note
F$GETSYI ("CWLOGICALS") always returns a value of FALSE on a
noncluster system. Procedures that are designed to run in both clustered
and nonclustered environments should first determine whether they are
in a cluster and, if so, then determine whether clusterwide logical names
are initialized.
5.6 Coordinating Startup Command Procedures
Immediately after a computer boots, it runs the site-independent command
procedure SYS$SYSTEM:STARTUP.COM to start up the system and control the
sequence of startup events. The STARTUP.COM procedure calls a number of
other startup command procedures that perform cluster-specific and node-specific
tasks.
The following sections describe how, by setting up appropriate cluster-specific
startup command procedures and other system files, you can prepare the
OpenVMS Cluster operating environment on the first installed computer before
adding other computers to the cluster.
Reference: See also the OpenVMS System Manager’s Manual for more
information about startup command procedures.
Preparing a Shared Environment 5–13