Understanding the Basic Components › Tape Mount Interception › Multiple File Processing to Virtual Volumes

Multiple File Processing to Virtual Volumes

Multiple file processing or stacking to Virtual Volumes is supported, but not typically needed for most application data sets.

Stacking to Virtual Volumes makes sense when running backup jobs which write a data set for each data set or table being backed up. For example, a job backing up 100 data sets or tables writing one data set or table per Virtual Volume would select 100 scratch VOLSERs, update those 100 VOLSERs in the Global VCAT, and allocate 100 files. If the data sets or tables fit on five full Virtual Volumes if stacked, the time spent performing these tasks would be reduced by 95 percent. These types of jobs run faster when stacking than not stacking.

CA Vtape limits the number of files per Virtual Volume to 256 for 400-MB and 800-MB Virtual Volumes. Higher capacity Virtual Volumes have a limit of 9999 files per Virtual Volume. When the file limit is reached, CA Vtape indicates an end of volume condition and performs a volume switch.

If more than one data set is written to a Virtual Volume, all data sets assume the same group number as the first volume data set. The group number determines the volume pool from which the virtual VOLSER is selected.