z/OS DFSMSdfp Storage Administration
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The use of expiration attributes and retention limit

z/OS DFSMSdfp Storage Administration

DFSMShsm determines if a data set has expired based on the expiration date found in the catalog entry of the data set. OAM determines if an object has expired based on the expiration date in its object directory entry. If an expiration date is not found, DFSMShsm and OAM use the management class expiration attributes. These attributes are used as follows:
  • If both expiration attributes are NOLIMIT, the data set or object never expires.
  • If one of the expiration attributes is NOLIMIT, then the other attribute must be satisfied.
  • If neither expiration attribute is NOLIMIT, both of the expiration attributes must be satisfied.
Tip: If you want to change the expiration date in a catalog entry, you can either use the access method services ALTER command or you can specify either the RETPD or EXPDT parameter in the JCL for an old managed non-VSAM data set, as long as the new expiration date is valid based on the retention limit specified. See z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support for information on changing the expiration date of an object.

Data sets or objects having the INTERIM management class defined in Defining management class expiration attributes become eligible for expiration when both of the following criteria are met: at least seven days since allocation and not referenced in the last two days.

Table 1 shows several combinations of retention attributes used for space management processing. Use the highlighted values for each instance.
Table 1. Comparing Retention Period Attributes
Attribute Case 1 Case 2 Case 3 Case 4 Case 5
Retention Limit 0 50 100 NOLIMIT 100
Expire after Days Non-usage 50 50 50 50 50
Expire after Date/Days 100 100 100 100 100
RETPD/EXPDT 60 60 60 60
In the first case, the retention limit is zero, so DFSMShsm and OAM honor the values of 50 and 100 which are the values specified for Expire after Days Non-usage and Expire after Date/Days and ignore any user-specified or data class values. In Case 2, the management class expiration values are ignored because RETPD and EXPDT values have been specified or derived and the retention limit is nonzero. However, because the retention limit is less than the user-specified or data class values, 50 is saved and used to calculate the expiration date.

In Case 3, the user-specified or data class values fall within the retention limit. So, DFSMShsm uses the values of 60 and 60. OAM uses a RETPD value of 60, because OAM does not consider EXPDT.

In Case 4, the RETPD and EXPDT are used because the retention period value is NOLIMIT.

In Case 5, because no user-specified or data class derived values are available, DFSMShsm and OAM use the values specified in the management class expiration attributes which are shown on the Management Class Define panel.

After you specify the expiration attributes, issue the DOWN command to see the next page of the Management Class Define panel, on which you can specify the migration attributes.

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