Tape Mount Intercept Filters › Tape Mount Redirection › Using Esoterics or Generics

Using Esoterics or Generics

CA Vtape intercepts tape mounts by influencing the eligible device table built for the esoteric or generic used in the tape mount request. If the Virtual Devices are not in that eligible device table, CA Vtape will not intercept the mount request even if a filter match occurs. If an intercept was performed in this situation, the mount request would fail with an IEF391I error message or a dynamic allocation error reason code of 04E5 indicating that a tape subsystem eliminated all eligible devices. If your tape devices are over-genned, more devices are defined then actually exist, you may receive a unit required message with a WTOR request that an offline device be brought online.

In this situation the tape mount is ignored to avoid the delays caused by job and task ABENDs. The tape mount is serviced by whatever devices are referenced by the esoteric or generic used. An additional benefit of this protection feature is that it can be used as an additional filtering criterion if application JCL changes are allowed.

For example, a site has 3490 and 3590 tape hardware. The CA Vtape Virtual Devices are defined as 3490 drives and automatically included in the 3490 generic. The Virtual Devices are also added to the esoteric of CART which is the primary esoteric used by the applications. The Virtual Devices are not added to the esoteric of TAPE.

A data set name filter of “PROD./” is added to the CA Vtape filters. This filter would cause all scratch mounts using UNIT=3490 or UNIT=CART for data sets with a high-level qualifier of PROD to be intercepted. However, if UNIT=3590 or UNIT=TAPE was used for data set PROD.MASTER.FILE, it would not intercept it because the Virtual Devices are not in the 3590 generic or the TAPE esoteric.

After deciding which applications will use Virtual Volumes, the JCL and tasks for that application can be reviewed to ensure they use UNIT=3490 or UNIT=CART and the single data set name filter will cause all of their tape mounts to be intercepted and directed to Virtual Volumes. If these applications have specific tape data sets that fill 3590 cartridges, they can continue to use UNIT=3590 or UNIT=TAPE and not be intercepted.

Some sites have chosen to control the use of CA Vtape by using JCL changes. They create an esoteric of VTAPE containing only the Virtual Devices and code a single data set name filter of “/”. As applications and tape data sets were reviewed and a decision was made to send them to Virtual Volumes, the task or JCL was changed to use the VTAPE esoteric.

This technique greatly simplifies filter coding at the cost of requiring JCL changes.