┌────────────────────────────┐
VOLUME 444444 │          X.Y.Z '           │     Day 1
              └────────────────────────────┘
 
              ┌─────────────┬──────────────┐
VOLUME 555555 │    X.Y.Z "  │    A.B.C     │     Day 2
              └─────────────┴──────────────┘
Statistical volumes for X.Y.Z = 0.5
 
Statistical volumes for A.B.C = 0.5

An earlier version of X.Y.Z resided on another volume (444444) before volume 444444 was erased-on-scratch. However, data sets A.B.C and X.Y.Z" currently share a single volume (555555).

Since the volume mount analyzer only calculates statistical volumes for the latest version of a data set, A.B.C occupies 0.5 statistical volumes, and X.Y.Z occupies 0.5 statistical volumes. Volume 444444 has been erased-on-scratch, since it no longer contains current data.