Using the VARY DRDS technique

You can use a dynamic reconfiguration file to:

• Move a physical unit from one nonswitched line to another within the same NCP
• Add physical units to nonswitched lines, or add logical units to physical units under nonswitched lines
• Change the link station address of physical units under nonswitched lines
• Delete physical units from nonswitched lines and delete logical units from physical units under nonswitched lines
• Delete NCP frame-relay PUs

The NCP to be reconfigured must be active, and the resource to be deleted or moved must be inactive. Also, the NCP cannot recognize, move, or add requests unless the physical unit was active at some time before deactivating it to issue a VARY DRDS command on it.

Dynamic reconfiguration with a DR file should be used only as a temporary method; a new NCP should be generated to reflect the changes as soon as time permits. The NCP should be reloaded to reflect the permanent changes.

If you are coding a dynamic reconfiguration file:

1. The first definition statement in the file must be VBUILD TYPE=DR. Include ADD, DELETE, or MOVE statements for the changes you want to make. For each statement, provide VTAM® definitions for the resources you want to change.

   Code the proper value (LOCAL) for the DRTYPE operand on the ADD and DELETE definition statements to indicate that the dynamic reconfiguration operation is for a connection through the local peripheral node. The default (DRTYPE=NCP) does not work in this case.

2. File the dynamic reconfiguration file in the VTAM definition library.
3. Make sure that you have deactivated all resources that must be inactive.
4. Issue the VARY DRDS command to invoke dynamic reconfiguration using the dynamic reconfiguration file.
5. Issue the VARY ACT command to activate newly added resources and resources you deactivated for the reconfiguration.

   To automatically activate a resource added by dynamic reconfiguration, the status of the higher-level node should be ACTIVE, and ISTATUS=ACTIVE should be specified on the newly added resource.

   To automatically activate a moved physical unit and its logical units that have ISTATUS=ACTIVE coded, specify ACTIVATE=YES on the PU definition statement following a MOVE statement.

6. Check the results of the dynamic reconfiguration by issuing a DISPLAY command for the affected resources.

If the NODELST start option is in effect when you perform a dynamic reconfiguration, VTAM records the name of each dynamic reconfiguration file in the NODELST file. When you restart VTAM after a halt or a failure, you can automatically reapply the changes in the dynamic reconfiguration files by specifying the name of the NODELST file on the CONFIG start option.

If a physical unit was dynamically moved before VTAM failed, it cannot be moved during a warm start. The activation of resources precedes the processing of dynamic reconfiguration files during warm start. Because dynamic reconfiguration depends upon resources being inactive, dynamic reconfiguration move operations are not performed. Deactivate the PU and issue the VARY DRDS command again.