Replication Guide and Reference

Operating Capture for MVS

The replication administrator can use the commands in this section to perform the following Capture for MVS tasks:

• Starting
• Scheduling
• Stopping
• Suspending
• Resuming
• Reinitializing
• Pruning

You can submit the commands from TSO or the MVS console.

Before You Start the Capture Program

Before starting the Capture program, make sure you complete the following post-installation tasks:

• Define one or more replication sources and subscriptions as described in Chapter 8. "Working with Replication Sources" and Chapter 9. "Working with Replication Targets". This creates the following control tables that must be defined in the database where Capture is to run:
  • ASN.IBMSNAP_REGISTER
  • ASN.IBMSNAP_PRUNCNTL
  • ASN.IBMSNAP_CCPPARMS
  • ASN.IBMSNAP_TRACE
  • ASN.IBMSNAP_WARM_START
  • ASN.IBMSNAP_UOW
  • ASN.IBMSNAP_CRITSEC

    You can also create these control tables manually by running the DPCNTL.* file from the RUN SQL Files window.

• Bind the Capture program to the source server from which the Capture program will capture changes. Refer to the Capture for MVS program directory for information on running the bind program for Capture.

• Ensure that ASN.IBMSNAP_REGISTER has at least one entry in it by defining a replication source with the Data Capture Changes option.

Starting Capture for MVS

After you start the Capture program, it runs continuously until you stop it or it detects an error.

To start the Capture program:

1. Prepare the JCL for MVS by specifying the appropriate optional invocation parameters in the PARM field of the ASNLRNnn DD statement. Tailor the JCL to meet your site's requirements. Sample JCL appears in the program directory for Capture for MVS.

   An example of this line in the invocation JCL is:

   //ASNLRNnn EXEC PGM=ASNLRPnn,PARM='DB2_subsys_name NOTERM WARMNS NOPRUNE'
   

   where nn is the level of DB2 for MVS.

   Table 9 defines the optional parameters.

2. Submit the JCL from TSO or from the MVS console. Capture for MVS can run either as a batch job or a started task.

Table 9 defines the parameters.

Table 9. ASNLRP Invocation Parameter Definitions for MVS

Parameter Definition
DB2_subsys_name The default is DSN for the subsystem name. This must be the first parameter.
TERM  (default)  Terminates the Capture program if DB2 is terminated. NOTERM Keeps the Capture program running if DB2 is terminated with MODE(QUIESCE). When DB2 comes up, Capture starts in WARM mode and begins capturing where it left off when DB2 terminated. If DB2 terminates via FORCE or due to abnormal termination, the Capture program terminates even if you selected this parameter.
WARM  (default)  The Capture program resumes processing where it ended in its previous run if warm start information is available. If the Capture program cannot warm start, it switches to a cold start. Refer to "Warm and Cold Starts" for more information. WARMNS The Capture program resumes processing where it ended in its previous run if warm start information is available. Otherwise, it issues a message and terminates. With WARMNS, the Capture program does not automatically switch to a cold start. The Capture program leaves the trace, UOW, change data, and warm start tables intact. In case of errors, Capture terminates instead of switching to a cold start as when WARM is specified. Refer to "Warm and Cold Starts" for more information. COLD The Capture program starts up by deleting all rows in its change data table, UOW table, pruning control table, and trace table during initialization. Refer to "Warm and Cold Starts" for more information.
PRUNE  (default)  The Capture program automatically prunes the change data and the UOW tables that the Apply program has copied since the last pruning. NOPRUNE Automatic pruning is disabled. The Capture program prunes the change data and UOW tables when you enter the PRUNE command. See the PRUNE command for more information.
NOTRACE  (default)  No trace information is written. TRACE Writes debug trace messages to the standard output, stdout.

Scheduling Capture for MVS

Use either the $TA JES2 command or the AT NetView command to start Capture for MVS at a specific time. You must:

1. Create a procedure that calls Capture for MVS in the PROCLIB.

2. Modify the ICHRIN03 RACF module (or appropriate definitions for your MVS security package) to associate the procedure with a user ID.

3. Link edit the module in SYS1.LPALIB.

Stopping Capture for MVS

>>-F--jobname,STOP---------------------------------------------><
 

Purpose

Use the STOP command to stop the Capture program in an orderly way and commit the log records that it processed up to that point.

Usage

Enter this command from TSO or the MVS console before:

• Removing an existing replication source
• Modifying an existing replication source

Suspending Capture for MVS

>>-F--jobname,SUSPEND------------------------------------------><
 

Purpose

Use the SUSPEND command to relinquish MVS resources to operational transactions during peak periods without damaging the Capture program environment.

This command suspends the Capture program until you issue the RESUME command.

Usage

Enter the SUSPEND command from TSO or the MVS console.

Attention: Do not use SUSPEND when canceling a replication source. Instead, stop the Capture program by entering the STOP command.

Resuming Capture for MVS

>>-F--jobname,RESUME-------------------------------------------><
 

Purpose

Use the RESUME command to restart the Capture program if you suspended it using the SUSPEND command.

Usage

Enter the RESUME command from TSO or the MVS console.

Reinitializing Capture for MVS

>>-F--jobname,REINIT-------------------------------------------><
 

Purpose

Use the REINIT command to have the Capture program reread the ASN.IBMSNAP_REGISTER tables or the ASN.IBMSNAP_CCPPARMS table while it is running. Use this command when you add a new replication source with Control Center while the Capture program is running.

This command ensures that the Capture program recognizes the new replication source. It also rereads the ASN.IBMSNAP_CCPPARMS table for any changes made to the tuning parameters.

Attention: Do not use REINIT to reinitialize the Capture program after canceling a replication source or dropping a replication source table while the Capture program is running. Instead, stop the Capture program and restart it using the WARM option.

Usage

Enter the REINIT command from TSO or the MVS console.

Pruning the Change Data and Unit-of-Work Tables

>>-F--jobname,PRUNE--------------------------------------------><
 

Purpose

Use the PRUNE command to start pruning the change data (CD) table and UOW table if you used the NOPRUNE invocation parameter to disable pruning when you started the Capture program.

This command prunes the CD and UOW tables once.

Usage

Enter the PRUNE command from TSO or the MVS console. The Capture program issues the message ASN0124I when the command is successfully queued.

During pruning, if you stop or suspend Capture, pruning does not resume after you enter the RESUME command. You must enter the PRUNE command again to resume pruning.

Providing the Current Log Sequence Number

>>-F--jobname,GETLSEQ------------------------------------------><
 

Purpose

Use the GETLSEQ command to provide the current log sequence number and the timestamp. You can use this number to determine how far Capture has read the DB2 log.

Usage

Enter the GETLSEQ command from TSO or the MVS console. The Capture program issues the message ASN0125I indicating when the current log sequence number is successfully processed.

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