Hi Siva,
Great pointer
http://codingissue.wordpress.com/2012/06/05/how-to-find-or-validate-change-block-tracking-results-returned-by-vmware-api-3/
Using the MOB to invoke QueryChangedDiskAreas and thereby separating code from vSphere issues is genius. As simple as possible. Dude that's the way aha, aha I like it aha aha - all thumbs up.
Just putting a like there ;-)
--
Thomas G.