Recovery and data sets

The Database Recovery utility (DFSURDB0) performs database recovery at the data set level. If more than one data set has been lost or damaged and you are using the Database Recovery utility, you need to recover each data set separately.

If you are using the IMS Database Recovery Facility for z/OS®, all the lost or damaged data sets can be recovered in one recovery operation.

With DEDBs, using multiple area data sets reduces the need for recovery. If one copy of the area data set has an I/O error, you can create another copy online and drop the error copy.

If your database data sets are multi-volume OSAM data sets, make certain you are using the appropriate allocation specifications to ensure that all volumes get a primary extent.

In some cases, you do not need to delete and redefine data sets prior to recovering them. In fact, in cases where the deletion and redefinition of data sets is optional, doing so unnecessarily slows the recovery process.

You are required to delete and define data sets during the recovery process in the following cases:

• You are recovering VSAM database data sets by using the Database Recovery utility.
• You are recovering the output data sets of the integrated HALDB Online Reorganization function and the data sets are in a cursor active state.
• You are rebuilding a HALDB indirect list data set (ILDS) by using the HALDB Index/ILDS Rebuild utility.

You are not required to delete and define data sets during the recovery process in the following cases:

• You are recovering OSAM database data sets by using the Database Recovery utility and you include image copies as input to the utility.
• You are rebuilding a HALDB PHIDAM primary index by using the HALDB Index/ILDS Rebuild utility.

In cases where you are required to delete and redefine the data sets, when you must execute the delete and define step in the recovery process depends on the circumstances of the recovery. For example:

• If you are including an image copy as input to the Database recovery utility, delete and define the data set before you run the utility.
• If you are not including an image copy as input to the Database recovery utility, such as when you apply an image copy to the database in a prior step, delete and define the data set before applying the image copy.
• If you are executing the recovery JCL automatically when the GENJCL.RECOV command is issued, delete and define the data set before you issue the GENJCL.RECOV command.