Multiple volumes and multiple data sets

To place a single data set on multiple volumes, code the multiple volume serial numbers in the related DD statement or request a nonspecific volume. To request a nonspecific volume or volumes, you omit volume serial numbers from the DD statement. This is also called a scratch volume request. If you request specific volumes and cataloging, all the specified volume serial numbers are associated with the new data set in the catalog. If you use fewer volumes than you specify, you cannot retrieve the data set properly using the catalog.

To place multiple data sets on a single volume, code the same volume serial number on each of the related DD statements or use the VOLUME=REF parameter on the DD statements for the second and subsequent data sets volume. When you create or retrieve a data set of file sequence greater than one, you must use the LABEL parameter to specify the data set's sequence number. This is not required if retrieval is accomplished through the catalog.

To place multiple data sets on multiple volumes, code a set of volume serial numbers on each of the related DD statements or use the VOLUME=REF parameter. This collection of volumes is called an aggregate.

Note: VOLUME=REF cannot be used if you specified volume serial numbers for the referred-to data set and that data set was written on fewer volumes.

If you code a set of volume serial numbers for each of the standard labelled data sets, the system works most efficiently if the first serial number is for the last volume occupied by the preceding data set. This is possible only if the volumes do not contain standard labels.

For multiple data sets on multiple volumes, you must use the LABEL parameter to specify the sequence number of each data set, both when you create it and when you retrieve it, except when retrieval is accomplished through the catalog. The sequence number specified for each data set must indicate the position of the data set relative to the entire multi-volume group. You can retrieve data sets in a different order than they were written. However, with standard labelled tape, you will get a warning message, IEC709I or IEC710I. For SL and AL, OPEN reads the existing labels to determine their position within the volume group. From existing labels, OPEN calculates the appropriate position for the data set being opened. For unlabeled tapes, the system cannot determine data set positions in an existing multi-volume group after the first volume. Therefore, you should not use the catalog to retrieve such data sets.

All data sets on a RACF-protected volume are protected. Data sets that span multiple volumes should have all volumes protected under a single RACF, a component of the Security Server for z/OS, tape volume set profile. If a data set on a RACF-protected volume is extended to a new volume that is not RACF-protected, the new volume is defined to RACF as part of the same volume set as the previous volume. Therefore, RACF protection is automatically extended to the new volume.