Thanks for your reply, snekkalapudi.
In vCenter, I would see the "used storage" for the VDP appliance is 41.7GB, but when I login to the appliance I can see the total size should far more than that. e.g. I can see 1 file under /space/avarmar... p_cache.dat is already over 50GB. I get quite confused what is the exact size consumed and where the backup files are stored.