In some cases the backend node can be in state PARTIAL because file /DB/NODE-<NODE-ID>/allocatedspace inside the storage controller is empty, like :
/ # cat /DB/NODE-2759660694/allocatedspace
and in /var/log/messages inside the storage controller are the records like:
May 6 14:25:11 (none) user.info GROUPMON: Thread-3 : Allocated space mismatch - Node 2759660694 - current 0 actual 78012208911
The issue can be fixed in following way.
Inside the storage controller:
1. kill all groupmon processes (before killing them, check args with which groupmon is started);
2. delete the file /DB/NODE-<NODE-ID>/allocatedspace;
3. start groupmon.
The above mentioned steps were checked for onapp-store-install-3.1.3-6.noarch. After the steps are completed, the backend node should become ACTIVE.