RDF/IMP and IMPX System Management Manual (RDF 1.3+)

Entering RDFCOM Commands
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
8-95
Command Overview
Security Restrictions
You can issue the TAKEOVER command only if you are a member of the super-user
group.
RDF State Requirement
You can issue the TAKEOVER command only if the communication lines between the
backup and primary systems are down, or the monitor process is not running on the
primary system.
Usage Guidelines
The TAKEOVER command is customarily issued when the primary system fails or
otherwise becomes unavailable, and makes the backup database the primary database.
When you issue a TAKEOVER command, RDF determines whether the monitor process
is running on the primary system:
•
If the communications lines are operational and the monitor and extractor processes
are still running, the TAKEOVER command fails.
•
If the communications lines are down, RDF proceeds as if the monitor process is not
running and executes the TAKEOVER command.
If RDF is running with updating on, RDFCOM sends a takeover message to each RDF
process.
If RDF is running with updating off, RDFCOM stops the receiver process and starts the
monitor in takeover mode. The monitor then starts a receiver process and all updater
processes.
During a TAKEOVER operation, RDF completes all the processing it can on the backup
system, writes information about pending records (data audit records for which no
commit/abort records have been received on the backup system) to the exception file,
and stops RDF on the backup system. You should verify that the takeover was
completed successfully by checking the log for 724 or 725 messages. Message 724
indicates that the takeover completed successfully. Message 725 indicates that it did
not, and you should reissue the TAKEOVER command.
If a double CPU failure occurs and the receiver process pair or an updater process pair
fails during a takeover operation, you can resume the operation just by entering the
TAKEOVER command through RDFCOM again.
Caution. The TAKEOVER command is not a normal operational command. Operators
should never issue this command strictly on their own initiative. Issue this command only
when specifically told to do so by someone in high authority.
It is important to ensure that the RDFCOM session uses the appropriate RDF control
subvolume which is associated with the primary system for this TAKEOVER operation. To do
this, specify the RDF control subvolume through the OPEN command or on the RDFCOM
command line.