When setting up recovery files for the CA Datacom DBUTLTY program RECOVERY function, in what order are they concatenated?

Document ID : KB000021000
Last Modified Date : 14/02/2018
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Description:

When something happens to a CA Datacom/DB or CA Datacom/AD database file to cause the data to be incorrect or corrupted, it may be necessary to "back out" the database changes from a specific process. In some cases, it may be necessary to restore the data from a known backup point and then "roll forward" changes that had already been made. In many cases, multiple Recovery Files are needed. How are then coded in the JCL so that they are processed in the correct order?

Solution:

The RECOVERY function of DBUTLTY protects the integrity of the database. It provides the ability to restore a database or a portion of a database from a previously stable point (forward recovery), or to undo the transactions of one or more jobs that contaminated the database (backward recovery). With either forward or backward recovery, logging must be active for the tables to be recovered. Changes to the data in the database table are logged in the Log Area (LXX), and periodically moved to more permanent storage in Recovery files (RXX).

If forward or backward recovery will need to process transactions from more than one Recovery File (RXX), it is important that the files be coded in the JCL in the correct order to ensure they are processed correctly. Regardless of the type of recovery, the files allocated to the RXX DD Statement must be entered in the order they were created, from oldest to most recent.

For example, if using a GDG, and if three RXX files are needed, you might code it this way:

//RXX       DD  DISP=SHR,DSN=MY.RXX.FILE(-2),. . . 
//          DD  DISP=SHR,DSN=MY.RXX.FILE(-1),. . . 
//          DD  DISP=SHR,DSN=MY.RXX.FILE(0),. . .

or if using the absolute filenames:

//RXX       DD  DISP=SHR,DSN=MY.RXX.FILE.G0143v00,. . .
//          DD  DISP=SHR,DSN=MY.RXX.FILE.G0144v00,. . .
//          DD  DISP=SHR,DSN=MY.RXX.FILE.G0145v00,. . .