The Backstore Engine › Default Group and Subgroup

Default Group and Subgroup

The Group number is assigned during filter processing and the Subgroup during Externalization of a Virtual Volume. Under certain circumstances the Group Number is not assigned because a filter match did not occur. These circumstances include:

• A Virtual Device unit number is coded in the JCL with a data set name that does not match a filter.
• When a Virtual Device is allocated with one data set name and written to with another data set name that does not match a filter.
• A job ABEND occurs during or after mount processing and before the data set is opened.

When the Group Number is missing, CA Vtape will access the DefaultGroup attribute in the Dynamic Options Section of the parmlib and assign its value to the problem Virtual Volume. The default setting of this attribute is Group01. The Subgroup will be assigned according to the normal process of evaluating the expiration date of the Virtual Volume.

Recommendations:

• If you are going to customize CA Vtape to use multiple Groups, set the DefaultGroup value to a unique group not used by normal filter processing. This will allow you to monitor whether or not the DefaultGroup is being used and to correct the software or JCL that is bypassing normal filter processing.
• If a unique Group is used for the DefaultGroup value, periodically check the output of a LIST=BACKSTORE Report to see if the DefaultGroup value is being assigned to Virtual Volumes.
• Customize the DefaultGroup value in the Group Definitions Section of the parmlib and release its Backstore Subgroup Queues so its Virtual Volumes can be Externalized.