DBCTL enables you to use utilities that IMS™ provides to help with the backup and recovery of your databases. These utilities are listed below.
The database image copy utility, DFSUDMP0 is a batch utility that creates a copy of data sets within a database. For DEDBs, you can copy an area concurrently with DBCTL activity. You can also use concurrent image copy for full function DL/I databases.
If the databases are updated while the utility is running, all logs including the one that was being used when DFSUDMP0 was started, are needed for use with DFSURDB0. You need both the log and the image copy to give a complete "picture" of the database for recovery purposes.
If you have not created an image copy, the data set to be recovered is used as input to DFSURDB0.
The online database image copy utility, DFSUICP0, is a BMP that creates an output copy of a data set within a full function DL/I database while the database is allocated and being used by DBCTL.
If the databases are updated while the utility is running, all logs including the one that was being used when DFSUICP0 was started, are needed for use with DFSURDB0. You need both the log and the image copy to give a complete "picture" of the database for recovery purposes.
If you have not created an image copy, the data set to be recovered is used as input to DFSURDB0.
If system availability is a major concern for your installation, you will probably want to use this utility. It collects the changes from the other log data sets onto a single log, thus helping to speed recovery. Balance the benefits of using it against the overhead it incurs, and the fact that you may not need to use its output.
The database recovery utility uses a backup copy of your database together with either (or both) the change accumulation utility or the logs, and reapplies changes made since the backup copy to create a new, reconstructed, database.
The database recovery utility performs recovery at the data set level, or at the track level. Often, only a single data set of the database requires recovery. However, if more than one data set has been lost or damaged, you need to recover each one separately. If an I/O error caused the problem, you might need to recover only a single track instead of reconstructing the entire data set.
You can use these utilities together to perform recovery by updating a copy of the database with the changes logged since the copy was made, as shown in Figure 29. See the IMS Utilities Reference: Database manual manual and the IMS Operations Guide for further guidance on using the utilities, including any restrictions that may apply.