Page History

...

In some cases, randomly picking a new leader may not be an ideal outcome. There are no guarantees for guarantees log contents for non-ISR / ELR replicas. A replica more recently added to a replica set may not be as "caught up" as other replicas which have been in the replica set for longer. A pathological example would be a new replica added to the replica set after the partition became offline. This replica would have no data at all and if set as leader by unclean recovery there will be complete truncation of the log. 

Implementation of this KIP will provide a way for operators to "intelligently" recover offline topic partitions during emergencies. It would assist users who run without automated unclean elections ( unclean.leader.election.enable = false ) but may desire an improved "break glass if needed" option during emergencies. We propose implementing a new command line tool kafka-unclean-recovery.sh which will assist in recovering offline partitions based on log length. 

...