replication models

Models

• primary-replica(failover, replica readable)/multi-master/chain
• replica/ec
• push/pull
• sync/async

Dynamo      PUSH coordinator -> preference list next nodes in hash ring
Raft/ZK     PUSH master commit log -> majority ack
GFS/Hadoop  chain replication
ES          PUSH primary-replica model, master concurrently dispatch index req to all replicas
MySQL       PUSH master async PUSH to slaves binlog
Kafka       PULL(Fetch) ISR
redis
Ceph        PUSH primary-replica sync model with degrade mode 同步写入
Swift
Aurora      PUSH primary instance R(3)+W(4)>N(6)