Instance not fully removed

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The removal of a Db2 Data Gate from the web user interface did not remove all related entries from the Db2 for z/OS® communications database.

Symptoms

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 full text reads:

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 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 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';
  3. Drop the table space that was used to connect the Db2 Data Gate instance with the Db2 for z/OS source database. To identify this table space:
    1. Make sure you have cleaned the Db2 for z/OS communications database as described in step 2. It is important that the pairing between the Db2 Data Gate instance and the source database has been removed.
    2. Identify the table space by submitting the following SQL query. You can run the query, for example, from the Data Management Console of Cloud Pak for Data:
      SELECT TBSPACE FROM SYSIBM.SYSTABLESPACES WHERE TBSPACE LIKE 'dwa%'

      This will probably return just a single table space name. In most cases, this will be dwa0-1.

    3. Drop this table space. For example:
      DROP TABLESPACE 'dwa0-1'

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