Understanding Tape Retention › Retention Methods

Retention Methods

Retention methods determine how you will use CA TLMS to handle your retention requirements. Twelve retention types correspond to the methods discussed below, which you will specify on the retention control statements.

User exit TLMSXTRS is provided to allow you to devise additional retention methods, if necessary.

The following retention methods vary in the degree of automation involved:

• Manual-This method of retention does not use any automation. It places control of the data set in the hands of the user, rather than in the hands of the tape retention system. It is as though the data set is permanently on hold; it will never be automatically scratched or moved. Its status can only change if the VMF is manually updated.
• Catalog Based-The retention period lasts as long as the data set is cataloged. TRS automatically interrogates the z/OS catalog to see if the data set is cataloged. The tape volume is considered available for scratch or movement when the data set is:
  • Not cataloged, or
  • Cataloged to a different volume
    • This is a good way to control programmers' test tapes. As soon as the programmer is through with the tape, the data set is uncataloged. When TRS no longer finds the data set in the catalog, the tape is considered available for scratch or movement.

  This is also a good way to retain generation data groups (GDGs). When the oldest generation rolls off the catalog, the tape is considered available for scratch or movement.

• Immediate Movement-The tape qualifies for scratch or movement as soon as TRS runs. This is a good way to ensure that critical tape backups are automatically moved to the first off-site location as soon as possible after they are created.
• Cycle Related-A cycle is one version of a specific data set. When a job creates data set ABC.XYZ, multiple executions of that job create multiple cycles of the same data set. The most recently created data set is cycle 1. The rest of the data sets are numbered sequentially in order by descending creation date and time. The oldest version becomes available for scratch or movement when a specified number of cycles has been retained. (This concept is similar to GDG processing.)

  This is a good way to handle transaction-driven applications that create several log tapes. You can automatically retain the most current versions, which are the only ones that need to be retained for recovery purposes. It is especially good in situations where weekly or monthly data sets are created; you can automatically retain the current data set and the versions from the previous two months.

The following retention methods are all automatic and all use dates:

• Elapsed Days-A data set is retained at the current location until a specified number of days has passed; at that time the tape is available for scratch or movement. This method of retention can be used for data sets that are created daily in a scheduled production job and must be retained for a specified number of days.
• Days Since Last Used-A data set is retained at the data center until a specified number of days has passed since the last time the data set was used for input or output. The tape is then available for scratch or movement. This is a good way to handle data sets that have no predetermined retention period, like programmers' test tapes. For example, if you specify the number of days as 30, a data set that has not been referenced for 30 days will be scratched. Every use of the data set restarts the 30-day retention period. This way the tape is automatically scratched when the programmer stops testing with it.
• Keep Date-A data set is retained at the current location until its keep date has passed. The tape is then available for scratch or movement. The keep date is determined by CA TLMS in a variety of ways, which are explained in the following paragraphs. This is a good way to handle data sets that have retention periods that fluctuate depending on specific situations. It is also another good way to handle programmers' test tapes.

More information:

Types of Retention