Cleaning up the Db2 for z/OS communications database

Edit online

The removal of a Data Gate for watsonx instance from the web user interface sometimes does not remove all related entries from the Db2 for z/OS communications database. This can lead to problems if you try to reuse the instance name.

Symptoms

Note: This information only applies to instances that connect to Db2 for z/OS data sources.

Leftover entries in the Db2 for z/OS communications database lead to an error when you try to pair a new instance with the same route host and port to the same Db2 for z/OS subsystem or data sharing group. Instead, you see an error message like this:

Figure 1. Error message
Error message that is displayed if you want to reuse the name of an instance that could not be removed entirely

The text goes on like this:

Unable to pair source. The accelerator or Db2 Data Gate instance 
could not be added to the Db2 subsystem because the "DC1A777" accelerator 
or Db2 Data Gate instance uses the same IP address [...]

Causes

The leftover entries collide with the entries that the system tries to create for your new instance.

Resolving the problem

Delete the entries of your previous instance manually:
  1. Make a note of the accelerator name that is displayed in the error message. In the example in Figure 1, this name is DC1A777. This is the Data Gate name that you need in the next step.
  2. Delete the related entries from the Db2 for z/OS communications database by submitting the following commands. Replace Data Gate name with the accelerator name that you obtained in step 1.
    
DELETE FROM SYSACCEL.SYSACCELERATORS WHERE ACCELERATORNAME='Data Gate name';
DELETE FROM SYSACCEL.SYSACCELERATEDTABLES WHERE ACCELERATORNAME='Data Gate name';
DELETE FROM SYSIBM.LOCATIONS WHERE LINKNAME = 'Data Gate name';
DELETE FROM SYSIBM.IPNAMES  WHERE LINKNAME = 'Data Gate name';
DELETE FROM SYSIBM.USERNAMES  WHERE LINKNAME = 'Data Gate name';

You can now reuse the route hostname and port for a pairing to the same Db2 for z/OS subsystem or data sharing group.