Mit6.824-Lab Lab1 MapReduce Note1 MapReduce Lab2 Raft Note1 Raft2A 领导者选举和心跳 Note2 Raft2B 日志复制 Note3 Raft2C 持久化 Note4 Raft2D 日志快照 Lab3 KV Service Note1 KV Service 3 Lab4 Shard KV Service Note1 Shard KV Service