vDR locks snapshots upon failed backup
So if you've reviewed all the snapshot troubleshooting on the web and still have not found a solution to your problem you might be the victim of a bad vDR configuration.
We decided to give vDR a try in our Test and Dev environment to reduce backup licensing costs and ran into problem where if the vDR backup failed the snapshots would fill up the LUNs and we had no luck removing or consolidating them using any of the methods available.
The quick fix ended up being as follows:
1) Shut down the vDR appliance
2) Detach the disks with orphaned snapshots from the appliance
3) Verify and correct for space requirements on target LUNs
4) Create a new snapshot with vSphere client (or service console)
5) Delete snapshot with vSphere client (or service console)
6) All went well and we were back in business at this point
Investigating preventative measures at the moment, will update with findings.