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DB2 Replication Guide and Reference

Reverting to Version 1 with FALLBACK

You can revert to Version 1 by running the ASNMIG command with the FALLBACK action. You need to fall back from all Version 5 Apply program processes before you fall back from associated Version 5 Capture program processes. You can fall back from Apply program processes in whichever order you choose.

After you fall back to Version 1, you can use the same migration process as described in Migrating Data with MIGRATE. You cannot fall back to Version 1 after executing the CLEANUP action, because all unused Version 1 control tables and views are dropped.

When fallback occurs at the source server, ASN.IBMSNAP_CRITSEC, ASN.IBMSNAP_UOW, and ASN.IBMSNAP_CCPPARMS remain in their altered format with the additional or changed columns, which do not cause any conflicts with the Version 1 Capture and Apply programs.

If you successfully migrate both Capture and Apply and you subsequently used the Control Center to define new replication sources and subscriptions before falling back, all new Version 5 replication sources and subscriptions are lost. When this happens, the migration program issues an informational message.

Falling Back from an Apply Program Process

To fall back from Version 5 to Version 1 for an Apply program process:

  1. Stop the Version 5 Apply program that you are migrating.

  2. Enter the following commands: 

    1. set db2dbdft=mig_db


    2. ASNMIG FALLBACK D=mig_db T=rout_serv C=v5_ctrl_serv U=sub_id V=ver

      Where:

      mig_db
      Name of the migration database where the global control tables are stored. This is a required parameter.

      rout_serv
      Server where the routing table resides. This is a required parameter.

      v5_ctrl_serv
      Version 5 control server, which contains the control tables for the Apply program process. This is a required parameter.

      sub_id
      Subscriber ID of an Apply program process. This is a required parameter.

      ver
      Version of the migration data that you want to fall back to. If you do not specify this parameter, ASNMIG selects the latest version number. This is an optional parameter.
    Note:For the Windows 95 and Windows NT platforms, when you specify parameters with the ASNMIG command for the FALLBACK action, you must surround those parameters with double quotes.

  3. Examine the fallback report (FALLBACK.RPT) to determine if the program executed successfully.

  4. Make sure the Version 1 Apply program still exists on the target server where it will execute. To install the program, see DataPropagator Relational Guide (SC26-3399-05) for your particular platform.

  5. Bind the Version 1 Apply program as described in DataPropagator Relational Guide (SC26-3399-05) for your particular platform.

  6. Start the Version 1 Apply program as described in DataPropagator Relational Guide (SC26-3399-05) for your particular platform after you successfully execute the FALLBACK action.

When you start ASNMIG FALLBACK for a subscriber, the program performs the following actions:

  1. Creates subscriber.IBMSNAP_ROUTING, copies data from subscriber.IBMSNAP_ROUTING1 to it, then drops subscriber.IBMSNAP_ROUTING1.

  2. Copies back the information in the Version 5 common subscription tables to the subscriber.IBMSNAP_REF_CNTL table at the Version 1 control server. It matches the Version 1 DATA_SERVER, BASE_OWNER, BASE_TABLE, COPY_SERVER, COPY_OWNER, and COPY_TABLE to the Version 5 SOURCE_SERVER, SOURCE_OWNER, SOURCE_TABLE, TARGET_SERVER, TARGET_OWNER, and TARGET_TABLE, respectively.

If auto-registration is detected at the target server, FALLBACK instructs you to enter the following command to fall back the ASN.IBMSNAP_REGISTER and ASN.IBMSNAP_PRUNCNTL after the fallback of this Apply program process is complete: 

ASNMIG FALLBACK D=mig_db S=v5_targ_serv V=ver

Auto-registration occurs when the TARGET_SERVER, TARGET_OWNER, and TARGET_TABLE columns in the ASN.IBMSNAP.SUBS_SET and ASN.IBMSNAP.SUBS_MEMBR tables are the same as the SOURCE_SERVER, SOURCE_OWNER and SOURCE_TABLE columns in the ASN.IBMSNAP_REGISTER table at the target server.

You can fall back the ASN.IBMSNAP_REGISTER and ASN.IBMSNAP_PRUNCNTL tables after the fallback of this Apply program process is finished.

Falling Back from a Capture Program Process

To fall back from Version 5 to Version 1 for a Capture program process:

  1. Stop the Capture program.

  2. Enter the following commands: 

    1. set db2dbdft=mig_db


    2. ASNMIG FALLBACK D=mig_db S=source_serv V=ver

      Where:

      mig_db
      Name of the migration database where the global control tables are stored. This is a required parameter.

      source_serv
      Source server of Version 5. This is a required parameter.

      ver
      Version of the migration data that you want to fall back to. If you do not specify this parameter, ASNMIG selects the latest version number. This is an optional parameter.
    Note:For the Windows 95 and Windows NT platforms, when you specify parameters with the ASNMIG command for the FALLBACK action, you must surround those parameters with double quotes.

  3. Examine the fallback report (FALLBACK.RPT) to determine if the program executed successfully.

  4. Make sure the Version 1 Capture program is installed on the source server. To install the program, see DataPropagator Relational Guide (SC26-3399-05) for your particular platform.

  5. Bind the Version 1 Capture program as described in DataPropagator Relational Guide (SC26-3399-05) for your particular platform.

  6. Warm start the Version 1 Capture program as described in DataPropagator Relational Guide (SC26-3399-05) for your particular platform after you successfully execute the FALLBACK action.

When you start ASNMIG FALLBACK for a source server, the program performs the following actions:

  1. Drops the ASN.IBMSNAP_CD_CNTL view.

  2. Creates the ASN.IBMSNAP_CD_CNTL table, then copies data to it from the Version 1 ASN.IBMSNAP_CD_CNTL1 and Version 5 ASN.IBMSNAP_REGISTER tables based on the information in the ASN.GLOBAL_CD_CNTL table.

  3. Drops the ASN.IBMSNAP_CD_CNTL1 table.

  4. Drops the Version 1 pruning control views and creates their counterpart tables.

  5. Copies data from the Version 1 backup pruning control tables and the Version 5 ASN.IBMSNAP_PRUNCNTL table to the Version 1 pruning control tables.

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