Hi,
Since the volume is full you will not be able to do any kind of file operations until some
space is free.
Go to Storage -> Disks in ui and find a disk which you are sure is safe to delete and
you won't miss it.
Note down the disk id.
locate the disk directory under the volume mount.
cd /rhev/data-center/mnt/glusterSD/<hostname>:/vmstore/<disk-id>/images/
you will see three files there.
<disk-id>
<disk-d>.lease
<disk-id>.meta
Run the following
$ true >| ./<disk-id> #removes file contents without changing the directory
entry
Now you can remove the file safely.
Head over to Storage -> Disks and delete the entry from the ui.
I think this should help you clear up some storage.