When DFSMShsm recalls data sets from tape ML2 volumes, the tape remains allocated and mounted until DFSMShsm has processed all recall requests requiring only that volume, or a TAPERECALLLIMITS parameter has been met. For tape devices before IBM® 3480s, the additional requests are processed by file sequence order. For 3480 (single-file-format tape cartridge) and later tape devices, the additional requests are processed by priority. When the recall queue no longer has any recall requests requiring that mounted tape volume, DFSMShsm sets a short timer and waits for another request. If a request needing that single tape arrives, it is started immediately. If the timer expires, DFSMShsm deallocates and demounts the tape volume.
To manage your space better and to reduce job-failure exposures, do not specify volume and unit information in JCL to refer to non-VSAM and VSAM data sets on DFSMShsm-managed volumes. If a non-SMS-managed volume is specified in the JCL, DFSMSdfp and DFSMShsm cannot cooperate in choosing the target volume for the recall. If the data set is non-SMS-managed, the specified non-SMS-managed volume is used as the target of the recall. If the data set is SMS-managed, the recall fails.
Relying on the standard catalog search allows DFSMShsm, DFSMSdfp, and DFSMSdss if specified, to cooperate in choosing the volume and recalling the data set during allocation processing.
The SETSYS VOLCOUNT(NONE | ANY) command affects how the allocation of SMS-managed data sets are performed when DFSMSdss is the datamover. The environment established by the SETSYS VOLCOUNT command can be overridden on command recalls by specifying the DFDSSOPTION(VOLCOUNT(N(nn) | ANY)) option of the RECALL command.