實現(xiàn)集群主從縮容【4/4】

接上一節(jié)，在當(dāng)前機器為4主4從的架構(gòu)上，減縮容量為3主3從架構(gòu)。即實現(xiàn)刪除6387和6388.
示意圖如下：

第一步：查看集群情況（第一次）

redis-cli --cluster check 127.0.0.1:6387

root@localhost:/data# redis-cli --cluster check 127.0.0.1:6387
127.0.0.1:6387 (bf73145e...) -> 1 keys | 4096 slots | 1 slaves.
122.114.161.116:6381 (6e961a47...) -> 1 keys | 4096 slots | 1 slaves.
122.114.161.116:6383 (78ac7be1...) -> 1 keys | 4096 slots | 1 slaves.
122.114.161.116:6382 (f097fec9...) -> 1 keys | 4096 slots | 1 slaves.
[OK] 4 keys in 4 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 127.0.0.1:6387)
M: bf73145e2eaaaa08084c9c2dad0d8c757faa48e1 127.0.0.1:6387slots:[0-1364],[5461-6826],[10923-12287] (4096 slots) master1 additional replica(s)
S: 4ed46e0368698cd9d5af2ee84631c878b8ebc4d0 12.114.161.16:6386slots: (0 slots) slavereplicates 6e961a4765b555189708bebb69badf7dfad25cd5
S: 664e456ae7d5cf27ea6583ba2f437dac11d4e767 12.114.161.16:6388slots: (0 slots) slavereplicates bf73145e2eaaaa08084c9c2dad0d8c757faa48e1
S: 9bc2417a9cd6545ef2445eb4aa0610d586acd73b 12.114.161.16:6385slots: (0 slots) slavereplicates 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2
M: 6e961a4765b555189708bebb69badf7dfad25cd5 12.114.161.16:6381slots:[1365-5460] (4096 slots) master1 additional replica(s)
S: 0e34147ce2544cd90f5cce78d5493ae9e8625dfe 12.114.161.16:6384slots: (0 slots) slavereplicates f097fec937f54d147d316c1c62e26cb67c9fd059
M: 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2 12.114.161.16:6383slots:[12288-16383] (4096 slots) master1 additional replica(s)
M: f097fec937f54d147d316c1c62e26cb67c9fd059 12.114.161.16:6382slots:[6827-10922] (4096 slots) master1 additional replica(s)
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

第二步：刪除從主機（6388）,刪除參數(shù)【--cluster del-node】

redis-cli --cluster del-node 12.114.161.16:6388 664e456ae7d5cf27ea6583ba2f437dac11d4e767

root@localhost:/data# redis-cli --cluster del-node 12.114.161.16:6388 664e456ae7d5cf27ea6583ba2f437dac11d4e767
>>> Removing node 664e456ae7d5cf27ea6583ba2f437dac11d4e767 from cluster 12.114.161.16:6388
>>> Sending CLUSTER FORGET messages to the cluster...
>>> Sending CLUSTER RESET SOFT to the deleted node.

第三步：查看集群情況（第二次）

redis-cli --cluster check 127.0.0.1:6387

略。。。

第四步：將該主機的槽位分給6381主機【--cluster reshard】

redis-cli --cluster reshard 12.114.161.16:6381

root@localhost:/data# redis-cli --cluster reshard 12.114.161.16:6381
>>> Performing Cluster Check (using node 12.114.161.16:6381)
M: 6e961a4765b555189708bebb69badf7dfad25cd5 12.114.161.16:6381slots:[0-6826],[10923-12287] (8192 slots) master1 additional replica(s)
S: 4ed46e0368698cd9d5af2ee84631c878b8ebc4d0 12.114.161.16:6386slots: (0 slots) slavereplicates 6e961a4765b555189708bebb69badf7dfad25cd5
M: bf73145e2eaaaa08084c9c2dad0d8c757faa48e1 12.114.161.16:6387slots: (0 slots) master
S: 9bc2417a9cd6545ef2445eb4aa0610d586acd73b 12.114.161.16:6385slots: (0 slots) slavereplicates 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2
S: 0e34147ce2544cd90f5cce78d5493ae9e8625dfe 12.114.161.16:6384slots: (0 slots) slavereplicates f097fec937f54d147d316c1c62e26cb67c9fd059
M: f097fec937f54d147d316c1c62e26cb67c9fd059 12.114.161.16:6382slots:[6827-10922] (4096 slots) master1 additional replica(s)
M: 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2 12.114.161.16:6383slots:[12288-16383] (4096 slots) master1 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)? 4096                  # 移除多少槽位數(shù)？
What is the receiving node ID? 6e961a4765b555189708bebb69badf7dfad25cd5     # 分給哪一臺master 主機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: bf73145e2eaaaa08084c9c2dad0d8c757faa48e1             # 從哪一臺主機移除的槽位 主機ID
Source node #2: done             # 輸入done即可 ，后面提示 直接輸入‘yes’即可
...
....

第五步：查看集群情況（第三次），確定需要移除主機的槽位數(shù)為0

redis-cli --cluster check 127.0.0.1:6387

root@localhost:/data# redis-cli --cluster check 122.114.161.116:6381  
122.114.161.116:6381 (6e961a47...) -> 2 keys | 8192 slots | 1 slaves.      # 此處顯示加上移除來的4096個槽位，總共有8192個槽位。轉(zhuǎn)移成功！
122.114.161.116:6387 (bf73145e...) -> 0 keys | 0 slots | 0 slaves.         # 此次顯示原來4096個槽位已經(jīng)移除，顯示為 0
122.114.161.116:6382 (f097fec9...) -> 1 keys | 4096 slots | 1 slaves.
122.114.161.116:6383 (78ac7be1...) -> 1 keys | 4096 slots | 1 slaves.
[OK] 4 keys in 4 masters.                                                  # 顯示總共4臺master主機
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 122.114.161.116:6381)
M: 6e961a4765b555189708bebb69badf7dfad25cd5 122.114.161.116:6381slots:[0-6826],[10923-12287] (8192 slots) master1 additional replica(s)
S: 4ed46e0368698cd9d5af2ee84631c878b8ebc4d0 122.114.161.116:6386slots: (0 slots) slavereplicates 6e961a4765b555189708bebb69badf7dfad25cd5
M: bf73145e2eaaaa08084c9c2dad0d8c757faa48e1 122.114.161.116:6387slots: (0 slots) master                                                 # 此次顯示原來Master主機的 4096個槽位已經(jīng)移除，顯示為 0              
S: 9bc2417a9cd6545ef2445eb4aa0610d586acd73b 122.114.161.116:6385slots: (0 slots) slavereplicates 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2
S: 0e34147ce2544cd90f5cce78d5493ae9e8625dfe 122.114.161.116:6384slots: (0 slots) slavereplicates f097fec937f54d147d316c1c62e26cb67c9fd059
M: f097fec937f54d147d316c1c62e26cb67c9fd059 122.114.161.116:6382slots:[6827-10922] (4096 slots) master1 additional replica(s)
M: 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2 122.114.161.116:6383slots:[12288-16383] (4096 slots) master1 additional replica(s)
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

根據(jù)上面的數(shù)據(jù)顯示，槽位已經(jīng)轉(zhuǎn)移成功！
【注意：如果想將4096個槽位平均分給另外三臺master主機，那么需要重復(fù)該操作三次，分別輸入不同的目標(biāo)ID即可！】

第六步：刪除master主機（6387）,刪除參數(shù)【--cluster del-node】

redis-cli --cluster del-node 12.114.161.16:6387 bf73145e2eaaaa08084c9c2dad0d8c757faa48e1

root@localhost:/data# redis-cli --cluster del-node 122.114.161.116:6381 bf73145e2eaaaa08084c9c2dad0d8c757faa48e1
>>> Removing node bf73145e2eaaaa08084c9c2dad0d8c757faa48e1 from cluster 122.114.161.116:6381
>>> Sending CLUSTER FORGET messages to the cluster...
>>> Sending CLUSTER RESET SOFT to the deleted node.

第七步：查看最終的集群情況（第四次）

redis-cli --cluster check 127.0.0.1:6387

root@localhost:/data# 
root@localhost:/data# 
root@localhost:/data# redis-cli --cluster check 122.114.161.116:6381                                            
122.114.161.116:6381 (6e961a47...) -> 2 keys | 8192 slots | 1 slaves.       # 該列表不在顯示6387端口的master主機了
122.114.161.116:6382 (f097fec9...) -> 1 keys | 4096 slots | 1 slaves.
122.114.161.116:6383 (78ac7be1...) -> 1 keys | 4096 slots | 1 slaves.
[OK] 4 keys in 3 masters.                                                   # 此次僅僅剩下3臺Master主機
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 122.114.161.116:6381)
M: 6e961a4765b555189708bebb69badf7dfad25cd5 122.114.161.116:6381slots:[0-6826],[10923-12287] (8192 slots) master1 additional replica(s)
S: 4ed46e0368698cd9d5af2ee84631c878b8ebc4d0 122.114.161.116:6386slots: (0 slots) slavereplicates 6e961a4765b555189708bebb69badf7dfad25cd5
S: 9bc2417a9cd6545ef2445eb4aa0610d586acd73b 122.114.161.116:6385slots: (0 slots) slavereplicates 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2
S: 0e34147ce2544cd90f5cce78d5493ae9e8625dfe 122.114.161.116:6384slots: (0 slots) slavereplicates f097fec937f54d147d316c1c62e26cb67c9fd059
M: f097fec937f54d147d316c1c62e26cb67c9fd059 122.114.161.116:6382slots:[6827-10922] (4096 slots) master1 additional replica(s)
M: 78ac7be13522bd4ffd6fcf900c6c149c6938ecc2 122.114.161.116:6383slots:[12288-16383] (4096 slots) master1 additional replica(s)
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

至此，成功將原來的“4主4從架構(gòu)”，縮容成“3主3從架構(gòu)”！