Re-install opennebula while there are working VM's

Please, describe the problem here and provide additional information below (if applicable) …

We have inherited a 5 node OpenNebula installation with Ceph as datastore. Ceph is configured on 3 nodes. There are 43 VM’s running controlled by KVM. OS is Debian Jessie.
Ceph is running fine, VM’s are also running. Opennebula seems running but it is not able to connect/manage any VM’s.
Log files indicates that there is a problem in zone configuration;
oned log;
Req:2032 UID:0 result FAILURE [] Error getting zone [0]
Cannot contact oned: [] Error getting zone [0]

Also when we look to the zone configuration from Sunstone, there are no zones defined.

We are planning to re-install OpenNebula.

My question is, if we re-install OpenNebula will it be able to see and manage already working

Can we do something else to fix this issue, like defining zone 0 on this installation.

Versions of the related components and OS (frontend, hypervisors, VMs):
OS : Debian 8 (Jessie)
Ceph : 11.2.1
OpenNebula : 5.4.6
Hypervisor : KVM