Deciding between the EXPDT and VRSEL retention methods

There are several things to be considered when deciding which retention method is the best for your volumes, multivolume sets, and the data sets on these volumes.

Considerations for data sets and volumes and volume sets subject to the EXPDT retention method:

All data sets on a volume or volume set are excluded from DFSMSrmm VRSEL inventory management processing. Only EXPROC processing is required to handle expiration of volumes managed by the EXPDT retention method.
When volumes are changed from being managed by the VRSEL retention method to be managed by the EXPDT retention method, you help reduce the processing that DFSMSrmm VRSEL inventory management must perform.
Volume sets managed by the EXPDT retention method can be retained by VOLUME, by SET, or by FIRSTFILE. The corresponding parmlib OPTION is RETENTIONMETHOD(EXPDT(RETAINBY())).
Note: The parmlib OPTIONs RETAINBY and MOVEBY apply to the VRSEL retention method only.
DFSMSrmm maintains a consistent expiration date and time for all data set records of a multivolume data set, except for multivolume data sets on volumes retained by FIRSTFILE.
Data sets can be retained based on their usage. The data set LASTREF extra days attribute causes the data set expiration date to be recalculated when the data set is used for a read or write operation.
Volumes containing data sets that are closed by ABEND processing or marked deleted or open are handled as if no special ABEND/DELETED/OPEN VRS had been defined. As they are not considered for the VRSEL processing, no VRS can be assigned.
Volumes managed by the EXPDT retention method are included only in the EXPDTDROP limit. VRSRETAIN and VRSDROP limits apply only to volumes managed by VRSEL retention method.
Return to scratch is attempted in a single run of inventory management EXPROC processing. (Similar as if the RELEASE(SCRATCHIMMEDIATE) release option had been used for volumes managed by the VRSEL retention method).
The EXPDT retention method does not control movement, so if you want to move a volume retained by the EXPDT retention method, you must move it manually. If you require DFSMSrmm to automatically manage the movement of a volume, use the VRSEL retention method instead.
You can specify that volumes purged from DFSMShsm are to be retained a few extra days to be sure that purged volumes do not contain any data that might still be needed. DFSMShsm migration and backup volumes can be retained by EXPDT=99365 and you can optionally set EXPDT to the current date or a future date when the volume is purged from DFSMShsm with EDGTVEXT. See the parmlib option TVEXTPURGE with the EXPIRE(days) subparameter.
Changes to vital record specifications will not affect data sets and volumes managed by the EXPDT retention method.
Any time you know when your volume is going to expire, just by looking at the expiration date.
EXPROC processing provides a summary of volumes by retention method.

Considerations for data sets and volumes subject to VRSEL retention method:

The VRSEL retention method uses vital record specifications to set policies for retention and automatic movement of your removable media. You can tailor you retention and movement policies in the vital record specifications according your needs.
DFSMSrmm VRSEL inventory management processing is needed to process the retention and movement policies specified in vital record specifications.
By excluding one or more of the data sets on your volume from VRSEL (VRSELEXCLUDE), you can have the volume managed just by those data sets not excluded from VRSEL. See CHANGEDATASET command. See the topic "Excluding data sets from VRSEL processing" in z/OS DFSMSrmm Implementation and Customization Guide for more information.
When a volume is dropped from retention (is not retained by a VRSEL any more) or if the data set or volume does not match to any vital record specifications, or your volume is not retained by set, then your volume is eligible for expiration processing
For detailed information on the VRSEL retention method, see:
Also see the topic in "How Expiration Processing Works " in z/OS DFSMSrmm Implementation and Customization Guide.