Hello,
thanks for your answer. Unfortunately there is no such thing as "provisioned space" in the datastore summary, so i got of track and tried with the performance manager, with which I couldn't get along at all...
But I finally found out (thanks to http://www.virtirl.com/?p=64 ) that you can calculate it yourself with data available from the datastore summary:
provisionedSpace = capacity - freeSpace + uncommitted
Kind regards,
Holger