[ovs-dev] [OVN][RAFT] Follower refusing new entries from leader

[taoyunupt]

Hi,
    My OVN cluster has 3 OVN-northd nodes, They are proxied by Haproxy with a VIP. Recently, I restart OVN cluster frequently.  One of the members report the logs below.
    After read the code and paper of RAFT, it seems normal process ,If the follower does not find an entry in its log with the same index and term, then it refuses the new entries.
    I think it's reasonable to refuse. But, as we could not control Haproxy or some proxy maybe, so it will happen error when an session assignate to the failed follower.
   
    Does have some means or ways to solve this problem. Maybe we can kick off the failed follower or disconnect it from the haproxy then synchronize the date ?  Hope to hear your suggestion.




2019-11-27T14:22:17.060Z|00240|raft|INFO|rejecting append_request because previous entry 1103,50975 not in local log (mismatch past end of log)
2019-11-27T14:22:17.064Z|00241|raft|ERR|Dropped 34 log messages in last 12 seconds (most recently, 0 seconds ago) due to excessive rate
2019-11-27T14:22:17.064Z|00242|raft|ERR|internal error: deferred append_reply message completed but not ready to send because message index 14890 is past last synced index 0: a2b2 append_reply "mismatch past end of log": term=1103 log_end=14891 result="inconsistency"
2019-11-27T14:22:17.402Z|00243|raft|INFO|rejecting append_request because previous entry 1103,50975 not in local log (mismatch past end of log)




[root at ovn1 ~]#  ovs-appctl -t /var/run/openvswitch/ovnsb_db.ctl cluster/status OVN_Southbound
a2b2
Name: OVN_Southbound
Cluster ID: 4c54 (4c546513-77e3-4602-b211-2e200014ad79)
Server ID: a2b2 (a2b2a9c5-cf58-4724-8421-88fd5ca5d94d)
Address: tcp:10.254.8.209:6644
Status: cluster member
Role: leader
Term: 1103
Leader: self
Vote: self


Log: [42052, 51009]
Entries not yet committed: 0
Entries not yet applied: 0
Connections: ->beaf ->9a33 <-9a33 <-beaf
Servers:
    a2b2 (a2b2 at tcp:10.254.8.209:6644) (self) next_index=15199 match_index=51008
    beaf (beaf at tcp:10.254.8.208:6644) next_index=51009 match_index=0
    9a33 (9a33 at tcp:10.254.8.210:6644) next_index=51009 match_index=51008