If an error occurs with the online XAR file, the XA resource service automatically swaps in the backup XAR file and continues uninterrupted operation. At this point, you can replace the failed online XAR file with a new file, allowing the transaction branches that were present before the error occurred to be recovered without having to shut down OpenTP1.

When the XA resource service is running using the backup XAR file, and you wish to replace the failed online XAR file with a new file, use the xarhold command to forcibly shut down the XA resource service. You will still be able to execute other OpenTP1 services.

To swap online XAR files at a failure:

1. Execute the xarhold command.
   The XA resource service shuts down.
   
2. Create a new online XAR file.
   Create this file on a different disk volume from that of the online XAR file that caused the error. Create the new online XAR file with the same record length and number of records as the backup XAR file.
   
3. Update the definition for the online XAR file in the XA resource service definition, to reflect the XAR file you created.
   Only change the definition of the online XAR file.
   
4. Execute the xarrles command.
   This releases the XA resource service from shutdown status. The transaction branches are recovered from shared memory, and the XA resource service resumes its online status using the newly created online XAR file.
   

The following figure shows how to swap XAR files when the online XAR file fails.

Figure 3-30 Swapping XAR files at failure of the online XAR file

Any failure of the backup XAR file, swapped in to allow continuous operation following an error with the online XAR file, will cause the XA resource service to shut down. If this occurs, OpenTP1 responds with the error code XAER_RMERR to every transaction instruction from an application server linked by the XA resource service. However, since the error is localized to the XA resource service, OpenTP1 continues running, and you can continue to execute OpenTP1 services with the exception of the XA resource service. Once you replace the XAR files with new files, you can recover the transaction branches of the XA resource service.

To replace the XAR file when both the online XAR file and the backup XAR file have failed and the XA resource service has shut down:

1. Create new XAR files.
   Create an online XAR file and a backup XAR file on a disk volume that is free from errors. These two files must have the same record length and number of records.
   
2. Update the definition for the XAR files in the XA resource service definition, to reflect the XAR files you created.
   Change the definitions for both the online and backup XAR files.
   
3. Execute the xarrles command.
   This releases the XA resource service from shutdown status. The transaction branches are recovered from shared memory, and the XA resource service resumes its online status using the newly created online XAR file.
   

The following figure shows how to swap XAR files when the backup XAR file fails.

Figure 3-31 Swapping XAR files at failure of the backup XAR file

If the online XAR file fails and OpenTP1 terminates (either normally or abnormally), the XA resource service shuts down. To restart the XA resource service, you create a new XAR file and then restart OpenTP1.

To replace the XAR file when the online XAR file fails and OpenTP1 has terminated:

1. Create a new online XAR file.
   Create this file on a different disk volume from that of the online XAR file that has failed. The new online XAR file must have the same record length and number of records as the backup XAR file.
   
2. Update the definition for the online XAR file in the XA resource service definition, to reflect the XAR file you created.
   Only change the definition of the online XAR file. Since the XA resource service recovers transaction branches from the backup XAR file, do not change the backup XAR file.
   
3. Restart OpenTP1.
   When you restart OpenTP1, the shutdown status of the XA resource service is released. The transaction branches are recovered from the backup XAR file, and the XA resource service restarts, using the newly created online XAR file.
   

Note

Before you can start OpenTP1 normally, or restart it, I/O access to both the online and backup XAR files must be possible. You cannot start OpenTP1 with a failed XAR file.

The following figure shows how to replace the XAR file when the online XAR file fails and OpenTP1 has been terminated.

Figure 3-32 Swapping XAR files at failure of the online XAR file with OpenTP1 not running

If both the online and backup XAR files fail and OpenTP1 terminates (either normally or abnormally), the XA resource service shuts down. This means that the transaction branches that were present before the error occurred cannot be recovered. To restart the XA resource service, create new XAR files, and then forcibly start OpenTP1 (forced normal start).

To replace XAR files when both the online and backup XAR files fail and OpenTP1 has terminated:

1. Create new XAR files.
   Create an online XAR file and a backup XAR file on a disk volume that is free from errors. These files should have the same record length and number of records.
   
2. Update the definition for the XAR files in the XA resource service definition, to reflect the XAR files you created.
   Change the definitions for both the online and backup XAR files.
   
3. Force OpenTP1 to start normally.
   When you restart OpenTP1, the shutdown status of the XA resource service is released. The XA resource service resumes its online status using the newly created online XAR file. However, transaction branches that were present before the error occurred are not recovered.
   

Note

Before you can forcibly start OpenTP1 normally, I/O access to both the online and backup XAR files must be possible. You cannot start OpenTP1 with a failed XAR file.

The following figure shows how to replace the XAR files when both the online and backup XAR files fail and OpenTP1 has terminated.

Figure 3-33 Swapping XAR files at failure of both the online and backup XAR files with OpenTP1 not running