Recovering control data sets

Allocate a spare ACDS and COMMDS when you allocate your originals. Having spare copies eases the recovery process if SMS cannot access the originals because of I/O errors. Place the spares on a device that every system in your complex can access. Make certain that they reside on a different device from your originals.

In order to support 32 names, an SMS control data set is converted from 8-name mode to 32-name mode. You must confirm this conversion, using the operator console or ISMF.

Restrictions and Recommendations:

If an SMS system temporarily goes down or has not yet been started with SMS, then it is not part of the system-managed storage environment. When you activate SMS on the system, it uses the ACDS and COMMDS that are specified in its IGDSMSxx member. If the COMMDS and ACDS are different from the ones used by the remainder of the SMS complex, then the system runs as a separate SMS complex.
Consequently, when you change the current ACDS or COMMDS, update the IGDSMSxx member of SYS1.PARMLIB for each system in the SMS complex.
Make copies of your control data sets before the system mode is converted for the following reasons:
- The conversion is permanent.
- You might want to maintain them for coexistence with down-level systems.
There are special considerations to keep in mind when you move control data sets and their catalog entries. See z/OS DFSMS Managing Catalogs for more information on special considerations, including the use of REPRO MERGECAT.