Create a derived metric that counts vmdk files for virtual machine

Hi

I'm trying to create a report that finds virtual machines that have phantom snapshots. I know the optimizer has this feature but I would like a simple report we can look at. I already have a query that looks for filles that have a bunch of zeros in the file name, but I also want to make sure that the number of files are greater then the number of hard disks. Any help would be appreciated.