Is there a way to tell of a vmfs5 datastore was simply upgraded from vmfs3(which lacks some vmfs5 features) or if it was created as a vmfs5 datastore without any upgrade used?
I figured it out myself. Look for the block size.
This method will only be valid if the VMFS3 datastore had a block size greater than 1MB.
Here is a possible solution for you;
http://communities.vmware.com/thread/418846?start=0&tstart=0