RDF System Management Manual for J-series and H-series RVUs (RDF 1.10)

\London and the control subvolume was BOSTON, then you would enter the following RDFCOM
command to the TACL prompt on \LONDON:
> RDFCOM BOSTON
The Takeover command has the ! option (see the syntax for this command in Chapter 8 ). If you
do not include the ! sign, then RDFCOM tries to see if the monitor and extractor are still running
on the primary system. If it can access the monitor or extractor because the primary system is still
running, then RDFCOM aborts the command immediately. If you include the ! option, then RDFCOM
does not try to reach the monitor and extractor on the primary system. The ! option also determines
whether or not you are prompted to confirm your intention of performing the Takeover operation,
a topic discussed a little further below.
It is highly recommended that you do not use the ! option because it prevents the Takeover command
from getting started if the primary system is still running. If this is the case and if you execute the
Takeover operation anyway, the result is that the primary and backup databases become out of
synchronization.
NOTE: If you do not use the ! option and if the primary system is down, then RDFCOM will need
to wait for the Expand level-4 timer to expire. This timer is usually set to 4 or 5 minutes, and this
means that the actual takeover processing does not commence until after the timer expires.
Compared to all the other non-RDF tasks that need to be completed before you can resume
application processing on your backup system, this short delay may not even be noticed.
If the communication lines are down or the monitor and extractor have failed when you issue the
TAKEOVER command, RDF executes the command on the backup system:
• If RDFCOM finds that the primary system is down or that the monitor and extractor do not
exist, then, depending on whether you included the ! option or not, RDFCOM prompts you to
confirm that you want the Takeover operation to proceed.
– If you did not include the ! option, then RDFCOM reports several informational messages
and then asks the following prompt: "Are you sure you want to TAKEOVER?"
You respond with "yes" or "no". If you respond "no", the operation immediately terminates.
– If you did include the ! option, then you are not prompted and the operation proceeds.
• If RDF is running with updating off, RDFCOM stops the receiver and purger processes, and
then it starts a local RDF monitor process on the backup system in takeover mode. The monitor
then starts the receiver, purger, and all updater processes. (The name of this monitor on the
backup system is generated by the system.)
• If RDF had been stopped, RDFCOM starts the monitor in TAKEOVER mode. The monitor then
starts the receiver, purger, and all updater processes. (The name of this monitor is generated
by the system.)
If a monitor process was started on the backup system, the monitor stops after the other RDF
processes have all shut down.
The following example shows how to use the TAKEOVER command when RDF is running with
updating enabled. The command sequence in the example causes the backup system \TORONTO
to take over processing from the primary system \SANFRAN.
1. At the TACL prompt on the backup system (\TORONTO), start an RDFCOM session and
specify the control subvolume name:
>RDFCOM SANFRAN
2. At the RDFCOM prompt, issue the TAKEOVER command:
]TAKEOVER
RDF displays the following prompt message:
*** TAKEOVER assumes a disaster on \SANFRAN has occurred.
Are you sure you want to TAKEOVER?
132 Critical Operations, Special Situations, and Error Conditions