redis cluster command

1.列出集群中的slot分配

cluster slots

1) 1) (integer) 10923   2) (integer) 16383   3) 1) "127.0.0.1"      2) (integer) 7002   4) 1) "127.0.0.1"      2) (integer) 70052) 1) (integer) 5461   2) (integer) 10922   3) 1) "127.0.0.1"      2) (integer) 7001   4) 1) "127.0.0.1"      2) (integer) 70043) 1) (integer) 0   2) (integer) 5460   3) 1) "127.0.0.1"      2) (integer) 7000   4) 1) "127.0.0.1"      2) (integer) 7003

2.列出集群中的节点

Cluster nodes

10332dcc956ed930789572f431d25730b9341ba9 127.0.0.1:7002 master - 0 1428550980814 3 connected 10923-16383e956d0f4cbe4a0ee688d7d561088d8878738274b 127.0.0.1:7001 master - 0 1428550982315 2 connected 5461-1092288a78c882554a45039967becd489c27b120cf8ff 127.0.0.1:7000 myself,master - 0 0 1 connected 0-5460a86e9770d1783edc1ed3753a4b784c1a41126cdc 127.0.0.1:7005 slave 10332dcc956ed930789572f431d25730b9341ba9 0 1428550982815 6 connected130e772599b1f0fce606f58794ebd962d0ab8963 127.0.0.1:7003 slave 88a78c882554a45039967becd489c27b120cf8ff 0 1428550982815 4 connecteddfa1b2444a1c3200a9d1c9be858b47f0e3756f3f 127.0.0.1:7004 slave e956d0f4cbe4a0ee688d7d561088d8878738274b 0 1428550981315 5 connected

3.查看集群信息

cluster info

cluster_state:okcluster_slots_assigned:16384cluster_slots_ok:16384cluster_slots_pfail:0cluster_slots_fail:0cluster_known_nodes:6cluster_size:3cluster_current_epoch:6cluster_my_epoch:1cluster_stats_messages_sent:291518cluster_stats_messages_received:291518

4.查询key的keyslot值

cluster keyslot “hello”

127.0.0.1:7000> cluster keyslot hello(integer) 866

5.执行failover

CLUSTER FAILOVER [FORCE|TAKEOVER]

FORCE 直接进入第4步，特别适用于主挂了的情况，特别注意，主服务要数量能够达到failover最低值。
TAKEOVER 慎用，适用于FOECE搞不定的情况。

failover过程：

1.The slave tells the master to stop processing queries from clients.从告诉主停止处理客户端请求。2.The master replies to the slave with the current replication offset.主服务告诉从服务现在的复制偏移量（就是复制到哪了，主会记录每个从的复制进度）。3.The slave waits for the replication offset to match on its side, to make sure it processed all the data from the slave before to continue.从服务根据主服务返回的复制偏移量和自己保存的值对比，确保数据一致。4.The slave starts a failover, obtains a new configuration epoch from the majority of the masters, and broadcast the new configuration.启动failover就，获取投票epoch，广播配置。 5.The old master receives the configuration update: unblocks its clients and start replying with redirection messages so that they'll continue the chat with the new master.旧主收到配置更新，下台。