Method for controlling application transaction status

Batch image copy process

The batch image copy process creates clean image copies that contain committed database records.

You can also use the batch image copy process when you want to measure the health of databases. Because all database records in the database are committed, you can run the HASH Check function or collect sensor data from the image copies.

The batch image copy process requires that all application transactions be stopped while the image copies are created. Spending additional efforts to manually stop and restart application transactions or the database each time you create image copies might not be an ideal approach. IMS HP Image Copy supports the following two options to avoid such additional efforts.

Quiesce the database by using IMS Tools Online System Interface

You can request to quiesce the database using IMS Tools Online System Interface, which issues the UPDATE DB QUIESCE command to quiesce the database. When the database is quiesced, no updates to the database will be in progress, all prior updates are committed and written to DASD, and application programs with new updates for the database are held in a wait state until the database is released from its quiesce state. Therefore, you can create clean image copies. After the image copies are created, the interface issues the UPDATE DB QUIESCE command again to release the quiesce state.

To reduce the time that application programs are held in a wait state, consider using this method together with the COPY or FDUMP option of Advanced Image Copy Services.

You can request to quiesce the database and release the quiesce state of the database by specifying the TOIAUTO_Q keyword.

Stop the database by using IMS Tools Online System Interface

If you request to stop the database through IMS Tools Online System Interface, the interface issues the /DBD or /DBR command to stop the database. Therefore, you can create clean image copies. After the image copies are created, the interface issues the /START command to restart the database.

This method can also be used to start an offline database after the database is initialized or reorganized. The Image Copy function creates image copies of the offline database and registers the image copies to the RECON data sets, then the interface issues the /START command to bring the database online. This method allows you to start using the database immediately after the database is initialized or reorganized.

You can request to stop and restart the database by specifying the TOIAUTO keyword.

Concurrent image copy (CIC) process

With this method, you can create image copies without stopping application transactions. Because the database records in the created image copy data sets are not committed, you must use a log data set or change accumulation data set during database recovery.

The following requirements must be met to apply the concurrent image copy process:

• Database, database data sets, and area data sets are registered to DBRC.
• DBRC is used in the job (DBRC=Y).

The following restrictions apply if the database uses KSDS:

• COPY and FDUMP options of Advanced Image Copy Services cannot be used.
• Image copies, except for those created with the DUMP option of Advanced Image Copy Services, cannot be used for database recovery.
• If you specify CIC_KSDS=N, the Image Copy function does not create image copies of KSDS.

You can request the concurrent image copy process by using the CIC or ACIC statement.