Because an extensive list of export volume candidates could take considerable time to complete, it might be necessary to cancel an export operation to expedite other processing or to quiesce the library activity in preparation for maintenance. The LIBRARY EXPORT,volser,CANCEL command or the CBRXLCS external services programming interface FUNC=EXPORT with the cancel option can be used for this purpose. A cancel from the host is normally effective immediately, except for the period of time when host purge processing is occurring for logical volumes being exported to the exported stacked volume. In this case, the host cancel takes effect after host purge processing is completed for the exported stacked volume.

The host cancellation method is the preferred method for canceling an export operation. However, in addition to host cancellation methods, you can also explicitly cancel an export operation at the library manager if there is no host available to cancel the export operation. Differences in the cancel methods will occur during host purge processing. If the explicit cancel occurs during host purge processing, the export operation terminates and logical volumes in the exported category are placed in the insert category (none of these logical volumes will be exported) and the host will perform insert processing on these logical volumes when it is available. The exported stacked volume will go back into the pool of usable scratch stacked volumes.

The status of all logical volumes requested for export is found in the status file of the export list volume after the export operation completes. Exported stacked volumes that were completed and placed in the export hold category before the cancel are not affected by the cancel.