VOLPERC not correct for VTS volumes

Document ID : KB000106135
Last Modified Date : 12/07/2018
Show Technical Document Details
Question:
The VOLPERC Field in the TMC Volume Record is not correct for virtual volumes in our IBM VTS library.
It always is VOLPERC= 001. What is the reason for this?
Answer:
VOLPERC and FILE-PERC are not valid for virtual-volumes, since by definition all virtual-volumes are 100% full when they are dismounted (all residual DISK cache is released). However, the actual amount of data written (as tracked by BYTE-PERC and COMPRESSION ratios) are accurate. We have had clients compare the CA 1 recorded values (taking BYTE-PERC and COMPRESSION into account) and compare the result against what the TS77xx says is in cache for the virtual-volume and the results are within the +/- 1/2% that we expected.