You're right. I thought Veeam was coming back with a different number then from vC but I was just looking at two similarly named VM's that have different amount of used storage.
The size of my ESX environment has far outgrown my ability to manage its backup jobs by hand. The script will compare a list of the all the VM's in vC to a list of the VM's currently being backed up by Veeam. All that are not in a backup job will be grouped by OS (to maximize dedupe, there may be other groupings I haven't thought of yet) and put them into jobs of 25 VM's or max job disk size of 2TB. Once either of these limits are reached new backup jobs will be created to accommodate.
Aslo, If a currently backed VM no longer exists in vC it will be excluded/removed from its backup job.
Why those limits:
1) To have the jobs finish with in our backup window.
2) Through trial and error 25 VM's has been an optimal number to process in any one job.
3) I am presenting multiple luns to my backup servers as targets as to not suffer from I/O contention. So I don't want jobs to take more space than I present to them.
The following Using powershell to set VSS creds
will be issue with my plans to totally automate this process.