Create a consolidated view of all separate environments via the Windows Client, and just open a TOTALS window for this view:
< see attached screen-print >
This will show all SYSPLEXES (where usually one ‘Parent’ Vantage runs, and additionally some small ‘child’ Vantages on other LPARs, which do no DTOCSCAN, POOLSCAN, GOA, etc…
and a TOTAL SUMMARY for all lines in the Totals Window.
However, it is not possible to create a Summary Object for this data, e.g. to log and trend the total installed and used storage.