/RTAKEOVER command

The remote takeover causes the tracking subsystem to finish processing and shut down.

Subsections:

• Environment
• Syntax
• Usage notes
• Examples

Environment

The following table lists the environments (DB/DC, DBCTL, and DCCTL) in which you can use the commands and keywords.

Syntax

/RTAKEOVER for an active subsystem

>>-+-/RTAKEOVER-+--+-FREEZE-+----------------------------------><
   '-/RTA-------'  '-DUMPQ--'   

/RTAKEOVER for a tracking subsystem

>>-+-/RTAKEOVER-+--UNPLAN--+-----------+-----------------------><
   '-/RTA-------'          '-NOREVERSE-'   

Usage notes

If entered on an active subsystem, /RTAKEOVER also causes the active subsystem to shut down. Once the remote tracking subsystem has shut down and remote takeover has successfully completed, one or more subsystems may be brought up in an active role at the secondary site and started with standard IMS restart commands.

Unless you specify the NOREVERSE keyword, a remote takeover can be reversed, even after the /RTAKEOVER command has been issued. The NORTA parameter on the CHANGE.SG command can be used to reverse a remote takeover.

This command can be issued to an IMSplex using the Batch SPOC utility.

/RTAKEOVER for an active subsystem

/RTAKEOVER is issued on the active IMS subsystem to initiate a planned remote takeover and must be specified with either the FREEZE keyword or the DUMPQ keyword.

/RTAKEOVER FREEZE indicates that a /CHECKPOINT FREEZE type of shutdown is performed before the planned takeover occurs.

/RTAKEOVER DUMPQ indicates that a /CHECKPOINT DUMPQ type of shutdown is performed before the planned takeover occurs. This form of takeover provides that all relevant log records reach the tracking subsystem such that no data is lost. This form of takeover allows the capability to rebuild the message queues during the new active start.

/RTAKEOVER must be entered for at least one IMS subsystem in the global service group (GSG) at the active site for which takeover is to occur. The other IMS subsystems at the active site must also be shut down, either with the /RTAKEOVER command, or some form of the /CHECKPOINT command that shuts the system down.

Once the active sends all of its log data sets, the active IMS subsystem shuts down. When all of the active subsystems in the global service group have shut down, the tracking subsystem then completes tracking work, stops online forward recovery (OFR), changes the role of the service group (tracking to active) in the RECON data set, and shuts down.

/RTAKEOVER for a tracking subsystem

/RTAKEOVER UNPLAN is issued on the tracking IMS subsystem to initiate an unplanned remote takeover after the active site fails unexpectedly. /RTAKEOVER UNPLAN causes the tracking subsystem to complete tracking work, stops online forward recovery (OFR), changes the role of the service group (tracking to active) in the RECON data set, and shuts down.

Recommendation:  Specify the NOREVERSE keyword to enable the tracking IMS subsystem to save and process all data it has received from the active site, regardless of whether that data was committed on the active IMS subsystem.

Although you can still reverse a remote takeover even if you specify NOREVERSE, you should not reverse it; in this case, you receive message DFS4122A when you restart the tracking subsystem.

If you do not specify NOREVERSE, the tracking IMS subsystem discards any uncommitted data it has received from the active subsystem.