3> 添加slave節點

下面為201:6382 master節點添加一個slave節點201:6383

shell> redis-trib.rb add-node --slave --master-id 901cade1bc2703ef2bb4ff49466b38762346755d 192.168.0.201:6383 192.168.0.201:6379

參數說明：
1> –slave：表示添加從節點
2> –master-id：master節點ID，這里用上邊新添加的主節點ID（201:6382）
3> 192.168.0.201:6383：新slave節點的IP和端口
4> 192.168.0.201:6379：集群中任意舊節點，只要能連上就可以。這里以201:6379為例

添加slave節點成功后集群中的節點狀態：

[root@localhost redis-3.2.0]# redis-cli cluster nodes
901cade1bc2703ef2bb4ff49466b38762346755d 192.168.0.201:6382 master - 0 1468333842665 9 connected 0-332 5461-5794 10923-11255
459dbcccc1e5be021f19efde794b9e84474c0c02 192.168.0.202:16379 slave b6814c717080de33907e6f769e1fd8dc4fe53c38 0 1468333841661 7 connected
9080c5049615730c66731b54cb084999009eeb52 192.168.0.201:6383 slave 901cade1bc2703ef2bb4ff49466b38762346755d 0 1468333843669 9 connected
06023f8283389ad5580c782797f49a5996c108b3 192.168.0.201:6379 myself,master - 0 0 1 connected 333-5460
91179b96d9b8abce85fa7a5748aa9b4114f0b260 192.168.0.202:16380 slave 06023f8283389ad5580c782797f49a5996c108b3 0 1468333844674 5 connected
ef8a49e5242c791551f1b317d5039144e38acde6 192.168.0.201:6380 slave 13567f6f8787d3aa3f4ef3abd15c2cc500a1469b 0 1468333842665 8 connected
b6814c717080de33907e6f769e1fd8dc4fe53c38 192.168.0.201:6381 master - 0 1468333845678 7 connected 5795-10922
13567f6f8787d3aa3f4ef3abd15c2cc500a1469b 192.168.0.202:16381 master - 0 1468333846685 8 connected 11256-16383

very good~ 可以看出，201:6383以成功添加為一個slave節點，并將201:6382作為master節點。

cluster nodes命令列表的節點狀態信息說明：

459dbcccc1e5be021f19efde794b9e84474c0c02 192.168.0.202:16379 slave b6814c717080de33907e6f769e1fd8dc4fe53c38 0 1468333841661 7 connected

1> 459dbcccc1e5be021f19efde794b9e84474c0c02 ：節點ID
2> 192.168.0.202:16379：節點IP和端口
3> slave：節點類型，master、slave或myself(master/slave)
4> b6814c717080de33907e6f769e1fd8dc4fe53c38 ：master節點ID，如果自己是master節點，這一列的值為0
5> 0：集群最近一次向節點發送 PING 命令之后， 過去了多長時間還沒接到回復。
6> 1468333841661：節點最近一次返回 PONG 回復的時間
7> 7：節點的配置紀元
8> connected：節點網絡連接狀態
9> 如果是主節點，節點狀態后邊顯示slot分配的范圍

3、改變slave節點的master

將上邊新加的slave節點（201:6383）的master，修改為201:6379（06023f8283389ad5580c782797f49a5996c108b3）

shell> redis-cli -h 192.168.0.201 -p 6383 cluster nodes | grep myself
9080c5049615730c66731b54cb084999009eeb52 192.168.0.201:6383 myself,slave 901cade1bc2703ef2bb4ff49466b38762346755d 0 0 0 connected

當前slave節點201:6383的master節點是901cade1bc2703ef2bb4ff49466b38762346755d

shell> redis-cli -h 192.168.0.201 -p 6383
192.168.0.201:6383> cluster replicate 06023f8283389ad5580c782797f49a5996c108b3

06023f8283389ad5580c782797f49a5996c108b3：新master節點的ID

192.168.0.201:6383> CLUSTER SLAVES 06023f8283389ad5580c782797f49a5996c108b3
1) "91179b96d9b8abce85fa7a5748aa9b4114f0b260 192.168.0.202:16380 slave 06023f8283389ad5580c782797f49a5996c108b3 0 1468336124600 1 connected"
2) "9080c5049615730c66731b54cb084999009eeb52 192.168.0.201:6383 myself,slave 06023f8283389ad5580c782797f49a5996c108b3 0 0 0 connected"

可以看出201:6383 slave節點已經是201:6379 master節點的子節點了。

4、刪除節點

1> 刪除slave節點

[root@localhost redis-3.2.0]# redis-trib.rb del-node 192.168.0.201:6383 9080c5049615730c66731b54cb084999009eeb52
>>> Removing node 9080c5049615730c66731b54cb084999009eeb52 from cluster 192.168.0.201:6383
>>> Sending CLUSTER FORGET messages to the cluster...
>>> SHUTDOWN the node.

參數說明：
1> del-node：刪除節點參數
2> 192.168.0.201:6383：節點IP和端口
3> 9080c5049615730c66731b54cb084999009eeb52：節點ID
節點成功刪除后，會同時將進程殺死

從節點重新恢復后，先cluster meet ip port將從節點加入集群，然后設置自己的mastercluster replication master_node_id

2、刪除master節點

注意：
1> 如果master節點有slot，必須先將所有slot分配給其它master節點。否則會提示你先將slot移除再嘗試刪除，如下所示：

shell> redis-trib.rb del-node 192.168.0.201:6382 901cade1bc2703ef2bb4ff49466b38762346755d
>>> Removing node 901cade1bc2703ef2bb4ff49466b38762346755d from cluster 192.168.0.201:6382
[ERR] Node 192.168.0.201:6382 is not empty! Reshard data away and try again.

2> 如果master節點有slave節點，先將slave節點移到其它master下

• 移除201:6382 master節點的slot
• [root@localhost redis-3.2.0]# redis-trib.rb reshard 192.168.0.201:6382
  >>> Performing Cluster Check (using node 192.168.0.201:6382)
  M: 901cade1bc2703ef2bb4ff49466b38762346755d 192.168.0.201:6382
  ? ?slots:0-332,5461-5794,10923-11255 (1000 slots) master
  ? ?1 additional replica(s)
  M: 06023f8283389ad5580c782797f49a5996c108b3 192.168.0.201:6379
  ? ?slots:333-5460 (5128 slots) master
  ? ?1 additional replica(s)
  ...
  [OK] All nodes agree about slots configuration.
  >>> Check for open slots...
  >>> Check slots coverage...
  [OK] All 16384 slots covered.
  How many slots do you want to move (from 1 to 16384)? 1000 # 201:6382一共1000個slot
  What is the receiving node ID? 06023f8283389ad5580c782797f49a5996c108b3 # 接收這1000個slot的節點ID
  Please enter all the source node IDs.
  ? Type 'all' to use all the nodes as source nodes for the hash slots.
  ? Type 'done' once you entered all the source nodes IDs.
  Source node #1:901cade1bc2703ef2bb4ff49466b38762346755d # 移除這1000個slot的master節點ID（這里同樣是201:6382）
  Source node #2:done
  ....
  Do you want to proceed with the proposed reshard plan (yes/no)? yes

• 新增master節點后，也進行了這一步操作，當時是分配，現在是去掉，反著的。

  • 刪除master節點
  • shell> redis-trib.rb del-node 192.168.0.201:6382 901cade1bc2703ef2bb4ff49466b38762346755d
    >>> Removing node 901cade1bc2703ef2bb4ff49466b38762346755dfrom cluster 192.168.0.201:6382
    >>> Sending CLUSTER FORGET messages to the cluster...
    >>> SHUTDOWN the node.g
  • 此時新的master節點也被刪除了，回到了添加節點之前的狀態。