When allocation processing for a new data set occurs at the operating system tape selection exit (Subsystem Interface 78), CA Vtape decides whether to intercept the allocation by accessing Data Set Name Filters and Data Class Filters. For more information about filters, see the chapter "Tape Mount Intercept Filters" in the z/OS Configuration Guide.
If the data set to be written matches an entry in the selection filters, CA Vtape marks all devices, except the Virtual Devices, ineligible in the Eligible Device List (EDL). If no matching entry is found in the selection filters, the Virtual Devices are marked ineligible. The System Resources Manager (SRM) then selects an eligible device from the modified EDL to service the allocation request.
If the esoteric device group or generic device type specified in the UNIT parameter does not contain the Virtual Device addresses, CA Vtape leaves the EDL unmodified.
If the UNIT parameter contains a specific device address that is defined as a CA Vtape Virtual Device, this device address is used, even if no data set matches an entry in the selection filters. CA Vtape must service the mount request.
Note: Oracle HSC, CSC, and SMC software also modify the EDL to influence tape allocation requests. If this software is not modified for the presence of CA Vtape, it can prevent CA Vtape from intercepting any allocation request by always marking the Virtual Devices ineligible. For the appropriate Oracle software changes, see the chapter “System Setup” in the Configuration Guide.
After SRM selects a Virtual Device for a new tape data set, the Virtual Device Engine detects the actual mount request and creates the Virtual Volume dataspace.
When allocation processing occurs at the operating system tape selection exit (Subsystem Interface 78) for an existing data set residing on a CA Vtape Virtual Volume, all devices except the CA Vtape Virtual Devices are marked ineligible in the Eligible Device List (EDL).
Note: The esoteric or generic specified in the UNIT JCL parameter or in the device type field of the data set catalog entry must contain Virtual Device addresses. If not, CA Vtape cannot intercept the mount request.
SRM selects the actual device from this list and requests a mount for a specific Virtual Volume on the selected Virtual Device.
When allocation processing for a new data set occurs at the operating system tape selection exit (Subsystem Interface 78), CA Vtape decides whether to intercept the allocation by accessing Data Set Name Filters and Data Class Filters.
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