Safeguards › How Safeguards Protect Data › Safeguards Detailed Description

Safeguards Detailed Description

To add safeguards to non-SMS VSAM data sets, CA Compress adds a special candidate volume to the catalog record for the data component of the data set. This volume has a serial number of "@ZSAM@". This serial number in the catalog is not apparent to users as long as the CA Compress subsystem is active. For example, an IDCAMS LISTCAT of the cluster does NOT show this volume in the listing when CA Compress is active. Nor do allocations of multiple volumes attempt to use this volume when CA Compress is active.

The implications of CA Compress adding Safeguards in this manner are as follows:

• After a data set is defined to CA Compress, the Safeguards are added to the data set the next time that it is accessed. The Safeguards are added without user involvement. When Safeguards are added, CA Compress writes a message to the operator, and it writes a message to SYSPRINT unless the started task specifies NOSGPRT to PGM=ZSUR through the PARM parameter.
• After the Safeguards are added, the data set can only be accessed when CA Compress is active on the CPU that is attempting the access. Special care must be taken when sharing an ICF catalog that contains CA Compress data sets across CPUs. CA Compress must be active on the CPU attempting access to the data set or the access fails.