Gluster users - Apr 2017 - Replica Out Of Sync - How to efficiently recover

Good morning guys,

We?re using GlusterFS 3.6.7 on RHEL 6.7 on AWS using multiple 1TB EBS GP2 disks
as bricks.
We have two nodes with several volumes using type Replicate and two bricks. 
1 brick belong to server #1 and, of course, the other one to server #2. 
Transport is over TCP and the only option reconfigured is performance.cache-size
which is tuned to 4GB.
Clients connect to those targets over FUSE with backupvolfile-server parameter
configured to server #2 and primary to server #1

Is worth to specify that those bricks host hundreds of thousands of
subdirectories which contains a lot of small xml files and images.

Couple of weeks ago one of the nodes goes down because of some AWS problem,
reboot was so quick that we don't even record this with agents so, because
daemon was not enable on autostart, brick two went out of sync of about 1+ TB.
When we realized this we immediatly tried to bring everything up and trigger the
self heal but it was literally killing our clients ending up with high iowait
and takes forever to retrieve content from the fuse share. Only option was kill
the sync process.

We tried using rsync and then trigger the self heal with no consistent result.
We tried to remove the bad brick, cleaning up the directory on second node and
the re-create it causing this massive iowait and the same exact situation.
We tried to clone the EBS of primary node, attach it to the secondary and then
try again with self heal with no consistent result.

We noticed that once brick two becomes online seems that is used as primary even
if configured on fstab as backupvolfile-server. I'm saying this because some
directories appear missing while is possibile to cd into which reflects the
brick status on secondary server.

Is there anything that you can suggest to solve this?
Are we missing something? 

Thanks a lot for any help.

Lorenzo