Response Time

CA Vtape response time is directly related to available MIPS and the DASD cache volume response times.

If the CPU is constrained, CA Vtape will run slower just like the other software and jobs executing on the LPAR. Jobs attempting to mount Virtual Volumes will experience elongated mount and run-times. Increasing the available MIPS or moving workloads that do not use CA Vtape to other LPARs or installing a zIIP engine can help in this situation.

If the DASD used for the CA Vtape cache has slow response times, CA Vtape reads and writes to that DASD will have slow response times. Jobs attempting to read and write Virtual Volumes will experience elongated run-times. There are a number of ways to address slow DASD response times. The following are some of the most affective ways to address slow DASD response times:

Defining Parallel Access Volumes (PAV) for the DASD cache volumes.
Moving the DASD cache volumes to another DASD box that supports faster access for sequential reads and writes.
Moving some of the DASD cache volumes to another DASD box that is not as busy.
Increasing the number of channels to the DASD box.