Forward recovery

Recovery of a database in a data-sharing environment is similar to recovery in a nonsharing environment. In both environments, use the Database Recovery utility (DFSURDB0) and give it the most recent image copy of the database, along with all pertinent log data sets used since you made that image copy.

Block-level data sharing, however, can require one additional step. Because more than one IMS system might update the database, you need the log from each IMS system to reconstruct the database. Furthermore, because these updates are most likely to be concurrent, you cannot submit those logs sequentially to the Database Recovery utility. Instead, you must first merge them by running the Database Change Accumulation utility (DFSUCUM0). Be sure to process all pertinent logs.

Even if you run change accumulation regularly, you must run the utility again before recovering the database so you merge the most recent logs with earlier logs.

However, you do not need to establish a valid set of logs for the Database Change Accumulation utility (DFSUCUM0). You can run DFSUCUM0 at any time without suspending operation of batch IMS systems, terminating database access for all but one online IMS system, or forcing a log switch on the remaining online IMS system. See Managing system logs.