Just a quick question. I have been searching and googling, but unable to find a solution.
Is there an easy way to get the consumed / In use disk space of a VM through the vCenter API?
Take a look at the HostDatastoreBrowswer object: HostDatastoreBrowser
The SearchDatastore_Task will return a results object which contains a FileInfo object with properties on the file. You can use this same method to get files that aren't associated with a VM.