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Control-M/Tape Retention Management determines how long the information contained in a data set or on a volume should be retained, and when that information can be overwritten.
The retention period of a data set is determined when the data set is created, according to the information specified through rules. The retention period of a volume is determined by the latest retention period of its data sets. Therefore, a volume becomes scratch only when all its data sets have been scratched.
A data set can only become scratch according to its retention parameters. It can only be overwritten (recreated or modified) if it is physically the last active data set on the volume.
There are two types of retention:
Table 4 Data Set Retention Types
Retention |
Description |
|---|---|
Normal Retention |
Established when the data set is closed properly. |
Abend Retention |
Applied if the data set is closed under abend, or not closed at all (for example, due to a system crash). |
The actual expiration of data sets and volumes is performed by a utility. This utility, that runs on a daily basis, performs the following functions:
Table 5 Functions Performed by Retention Utility
Function |
Description |
|---|---|
Retention Processing |
The retention specifications of all selected data sets are checked. Expired data sets are marked scratch in the Media Database. When all data sets on a volume are marked scratch, the volume becomes scratch. |
Report Production |
A report is produced that shows scratch volumes for a specific date. This report is an important tool for forecasting the availability of scratch volumes in each pool. |
Retention Period Recalculation |
If requested, the retention period of all or selected data sets and volumes is recalculated according to updated rules. |
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