The CONFIGURATION SET TIME command enables you to reset the
system time. Specify a time value using the following format:
[dd-mmm-yyyy[:]] [hh:mm:ss.cc]
You can also enter a delta time value. For more information about
time formats, see the OpenVMS User's Manual.
In an environment of individual nodes, SYSMAN sets the time to
the specified value on each node. Without a time specification,
SYSMAN sets the time according to the time-of-year clock on each
node.
In an OpenVMS Cluster environment, SYSMAN sets the time to the
specified value on each node. If you do not specify a value,
SYSMAN uses the time-of-year clock. In a local cluster, SYSMAN
reads the clock on the node from which you are executing SYSMAN
and assigns this value to all nodes in the cluster. In a remote
OpenVMS Cluster, SYSMAN reads the clock on the target node in
the cluster and assigns that value to all nodes. Note that the
time-of-year clock is optional for some processors; for more
information, see your processor handbook.
SYSMAN uses special processing in an OpenVMS Cluster environment
to ensure that all processors in the cluster are set to the same
time. Because of communication and processing delays, it is not
possible to synchronize clocks exactly. However, the variation
is typically less than a few hundredths of a second. If SYSMAN
cannot set the time to within one half second of the specified
time, you receive a warning message that names the node that
failed to respond quickly enough.
As a result of slight inaccuracies in each processor clock,
times on various members of a cluster tend to drift apart.
The following procedure synchronizes system times in a cluster
environment:
$ SYNCH_CLOCKS:
$ RUN SYS$SYSTEM:SYSMAN
SET ENVIRONMENT/CLUSTER
CONFIGURATION SET TIME
EXIT
$ WAIT 6:00:00
$ GOTO SYNCH_CLOCKS
The procedure sets the time on all cluster nodes to the value
obtained from the local time-of-year clock, waits 6 hours, then
resets the time for the cluster.