An orphaned or "Zombie" VMDK file refers to a virtual hard disk that is no longer in active use by a virtual machine or in the case of a VRA or journal disk, by Zerto.
These can be safely deleted.
A third-party tool called RV-Tools by RobWare can significantly assist in identifying these possible orphaned disks for safe deletion. It is a third-party tool and as such Zerto cannot provide support for it directly.
First log into RV-Tools and connect to the affected VCenter through hostname/IP and login credentials for an administrator account.
It will take a couple of minutes to fully scan the VCenter environment it is connected to.
Then click to VHealth tab. Any VMDK that shows with a message of "Possible a zombie vmdk file! Please check." is a good candidate for being an orphaned virtual that can be deleted to recover disk space.
It is considered a best practice not to delete suspected orphaned vmdk files right away but rather move them to another location out of the environment to see if anything breaks in their absence. If nothing breaks, then they can be assumed totally safe to delete.