1) Load some items
2) Rebooted node .15. (Firewall get turned now now)
3) Node 15 comes back up..
vb_replica_curr_items = 0 as all vbuckets are marked as dead.
During this time, ns_server does not detect that the node is unreachable or anything. Until we disable the firewall.
Disable the firewall, all replica vbuckets are set back correctly.