Redis Cluster叢集的搭建與實踐
阿新 • • 發佈：2018-12-23
Redis Cluster叢集
一、redis-cluster設計
Redis叢集搭建的方式有多種，例如使用zookeeper等，但從redis 3.0之後版本支援redis-cluster叢集，Redis-Cluster採用無中心結構，每個節點儲存資料和整個叢集狀態,每個節點都和其他所有節點連線。其redis-cluster架構圖如下：
其結構特點：
1、所有的redis節點彼此互聯(PING-PONG機制),內部使用二進位制協議優化傳輸速度和頻寬。
2、節點的fail是通過叢集中超過半數的節點檢測失效時才生效。
3、客戶端與redis節點直連,不需要中間proxy層.客戶端不需要連線叢集所有節點,連線叢集中任何一個可用節點即可。
4、redis-cluster把所有的物理節點對映到[0-16383]slot上（不一定是平均分配）,cluster 負責維護node<->slot<->value。
5、Redis叢集預分好16384個桶，當需要在 Redis 叢集中放置一個 key-value 時，根據 CRC16(key) mod 16384的值，決定將一個key放到哪個桶中。
1、redis cluster節點分配
現在我們是三個主節點分別是：A, B, C 三個節點，它們可以是一臺機器上的三個埠，也可以是三臺不同的伺服器。那麼，採用雜湊槽 (hash slot)的方式來分配16384個slot 的話，它們三個節點分別承擔的slot 區間是：
節點A覆蓋0－5460;
節點B覆蓋5461－10922;
節點C覆蓋10923－16383.
獲取資料：
如果存入一個值，按照redis cluster雜湊槽的演算法： CRC16('key')%16384 = 6782。 那麼就會把這個key 的儲存分配到 B 上了。同樣，當我連線(A,B,C)任何一個節點想獲取'key'這個key時，也會這樣的演算法，然後內部跳轉到B節點上獲取資料
新增一個主節點：
新增一個節點D，redis cluster的這種做法是從各個節點的前面各拿取一部分slot到D上，我會在接下來的實踐中實驗。大致就會變成這樣：
節點A覆蓋1365-5460
節點B覆蓋6827-10922
節點C覆蓋12288-16383
節點D覆蓋0-1364,5461-6826,10923-12287
同樣刪除一個節點也是類似，移動完成後就可以刪除這個節點了。
2、Redis Cluster主從模式
redis cluster 為了保證資料的高可用性，加入了主從模式，一個主節點對應一個或多個從節點，主節點提供資料存取，從節點則是從主節點拉取資料備份，當這個主節點掛掉後，就會有這個從節點選取一個來充當主節點，從而保證叢集不會掛掉。
上面那個例子裡, 叢集有ABC三個主節點, 如果這3個節點都沒有加入從節點，如果B掛掉了，我們就無法訪問整個叢集了。A和C的slot也無法訪問。
所以我們在叢集建立的時候，一定要為每個主節點都添加了從節點, 比如像這樣, 叢集包含主節點A、B、C, 以及從節點A1、B1、C1, 那麼即使B掛掉系統也可以繼續正確工作。
B1節點替代了B節點，所以Redis叢集將會選擇B1節點作為新的主節點，叢集將會繼續正確地提供服務。 當B重新開啟後，它就會變成B1的從節點。
不過需要注意，如果節點B和B1同時掛了，Redis叢集就無法繼續正確地提供服務了。
二、redis叢集的搭建
叢集中至少應該有奇數個節點，所以至少有三個節點，每個節點至少有一個備份節點，所以下面使用6節點（主節點、備份節點由redis-cluster叢集確定）。
下面使用redis-3.2.0安裝，下載地址
1、安裝redis節點指定埠
解壓redis壓縮包，編譯安裝
[[email protected] redis-3.2.0]# tar xzf redis-3.2.0.tar.gz
[[email protected] redis-3.2.0]# cd redis-3.2.0
[[email protected] redis-3.2.0]# make
[[email protected] redis01]# make install PREFIX=/usr/andy/redis-cluster在redis-cluster下 修改bin資料夾為redis01,複製redis.conf配置檔案
配置redis的配置檔案redis.conf
daemonize yes #後臺啟動
port 7001 #修改埠號，從7001到7006
cluster-enabled yes #開啟cluster，去掉註釋
cluster-config-file nodes.conf
cluster-node-timeout 15000
appendonly yes
複製六份，修改對應的埠號
2、安裝redis-trib所需的 ruby指令碼
複製redis解壓檔案src下的redis-trib.rb檔案到redis-cluster目錄
[[email protected] redis-cluster]# cp /usr/andy/redis/redis-3.2.0/src/redis-trib.rb ./安裝ruby環境：
[[email protected] redis-cluster]# yum install ruby
[[email protected] redis-cluster]# yum install rubygems安裝redis-trib.rb執行依賴的ruby的包redis-3.2.2.gem，下載
[[email protected] redis-cluster]# gem install redis-3.2.2.gem3、啟動所有的redis節點
可以寫一個命令指令碼start-all.sh
cd redis01
./redis-server redis.conf
cd ..
cd redis02
./redis-server redis.conf
cd ..
cd redis03
./redis-server redis.conf
cd ..
cd redis04
./redis-server redis.conf
cd ..
cd redis05
./redis-server redis.conf
cd ..
cd redis06
./redis-server redis.conf
cd ..
設定許可權啟動
[[email protected] redis-cluster]# chmod 777 start-all.sh
[[email protected] redis-cluster]# ./start-all.sh 檢視redis程序啟動狀態
[[email protected] redis-cluster]# ps -ef | grep redis
root 4547 1 0 23:12 ? 00:00:00 ./redis-server 127.0.0.1:7001 [cluster]
root 4551 1 0 23:12 ? 00:00:00 ./redis-server 127.0.0.1:7002 [cluster]
root 4555 1 0 23:12 ? 00:00:00 ./redis-server 127.0.0.1:7003 [cluster]
root 4559 1 0 23:12 ? 00:00:00 ./redis-server 127.0.0.1:7004 [cluster]
root 4563 1 0 23:12 ? 00:00:00 ./redis-server 127.0.0.1:7005 [cluster]
root 4567 1 0 23:12 ? 00:00:00 ./redis-server 127.0.0.1:7006 [cluster]
root 4840 4421 0 23:26 pts/1 00:00:00 grep --color=auto redis可以看到redis的6個節點已經啟動成功
殺死全部的幾點：
[[email protected] redis-cluster]# pkill -9 redis4、使用redis-trib.rb建立叢集
./redis-trib.rb create --replicas 1 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005 127.0.0.1:7006使用create命令 --replicas 1 引數表示為每個主節點建立一個從節點，其他引數是例項的地址集合。
[[email protected] redis-cluster]# ./redis-trib.rb create --replicas 1 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005 127.0.0.1:7006
>>> Creating cluster
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
127.0.0.1:7001
127.0.0.1:7002
127.0.0.1:7003
Adding replica 127.0.0.1:7004 to 127.0.0.1:7001
Adding replica 127.0.0.1:7005 to 127.0.0.1:7002
Adding replica 127.0.0.1:7006 to 127.0.0.1:7003
M: dfd510594da614469a93a0a70767ec9145aefb1a 127.0.0.1:7001
slots:0-5460 (5461 slots) master
M: e02eac35110bbf44c61ff90175e04d55cca097ff 127.0.0.1:7002
slots:5461-10922 (5462 slots) master
M: 4385809e6f4952ecb122dbfedbee29109d6bb234 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
S: ec02c9ef3acee069e8849f143a492db18d4bb06c 127.0.0.1:7004
replicates dfd510594da614469a93a0a70767ec9145aefb1a
S: 83e5a8bb94fb5aaa892cd2f6216604e03e4a6c75 127.0.0.1:7005
replicates e02eac35110bbf44c61ff90175e04d55cca097ff
S: 10c097c429ca24f8720986c6b66f0688bfb901ee 127.0.0.1:7006
replicates 4385809e6f4952ecb122dbfedbee29109d6bb234
Can I set the above configuration? (type 'yes' to accept): yes
>>> Nodes configuration updated
>>> Assign a different config epoch to each node
>>> Sending CLUSTER MEET messages to join the cluster
Waiting for the cluster to join......
>>> Performing Cluster Check (using node 127.0.0.1:7001)
M: dfd510594da614469a93a0a70767ec9145aefb1a 127.0.0.1:7001
slots:0-5460 (5461 slots) master
M: e02eac35110bbf44c61ff90175e04d55cca097ff 127.0.0.1:7002
slots:5461-10922 (5462 slots) master
M: 4385809e6f4952ecb122dbfedbee29109d6bb234 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
M: ec02c9ef3acee069e8849f143a492db18d4bb06c 127.0.0.1:7004
slots: (0 slots) master
replicates dfd510594da614469a93a0a70767ec9145aefb1a
M: 83e5a8bb94fb5aaa892cd2f6216604e03e4a6c75 127.0.0.1:7005
slots: (0 slots) master
replicates e02eac35110bbf44c61ff90175e04d55cca097ff
M: 10c097c429ca24f8720986c6b66f0688bfb901ee 127.0.0.1:7006
slots: (0 slots) master
replicates 4385809e6f4952ecb122dbfedbee29109d6bb234
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.上面顯示建立成功，有3個主節點，3個從節點，每個節點都是成功連線狀態。
3個主節點[M]以及分配的雜湊卡槽如下：
M: dfd510594da614469a93a0a70767ec9145aefb1a 127.0.0.1:7001
slots:0-5460 (5461 slots) master
M: e02eac35110bbf44c61ff90175e04d55cca097ff 127.0.0.1:7002
slots:5461-10922 (5462 slots) master
M: 4385809e6f4952ecb122dbfedbee29109d6bb234 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
3個從節點[S]以及附屬的主節點如下：
S: ec02c9ef3acee069e8849f143a492db18d4bb06c 127.0.0.1:7004
replicates dfd510594da614469a93a0a70767ec9145aefb1a
S: 83e5a8bb94fb5aaa892cd2f6216604e03e4a6c75 127.0.0.1:7005
replicates e02eac35110bbf44c61ff90175e04d55cca097ff
S: 10c097c429ca24f8720986c6b66f0688bfb901ee 127.0.0.1:7006
replicates 4385809e6f4952ecb122dbfedbee29109d6bb234
以上叢集安裝成功了，如果安裝未成功報如下錯誤
>>> Creating cluster
[ERR] Sorry, can't connect to node ....
需要安裝最新的ruby原始碼，下載
[[email protected] redis-cluster]# tar -zxvf ruby-2.3.1.tar.gz
[[email protected] redis-cluster]# cd
[[email protected] redis-cluster]# ./configure --prefix=/usr/local/ruby-2.3.1
[[email protected] redis-cluster]# make && make install
[[email protected] redis-cluster]#gem install redis 還有一種情況是，在VMware做測試的時間（都在一臺伺服器時），ip應該使用127.0.0.1，如果使用區域網ip，也會報節點建立失敗。
三、redis叢集的測試
1、測試存取值
客戶端連線叢集redis-cli需要帶上 -c ，redis-cli -c -p 埠號
[[email protected] redis01]# ./redis-cli -c -p 7001
127.0.0.1:7001> set name andy
-> Redirected to slot [5798] located at 127.0.0.1:7002
OK
127.0.0.1:7002> get name
"andy"
127.0.0.1:7002> 根據redis-cluster的key值分配，name應該分配到節點7002[5461-10922]上，上面顯示redis cluster自動從7001跳轉到了7002節點。
我們可以測試一下7006從節點獲取name值
[[email protected] redis06]# ./redis-cli -c -p 7006
127.0.0.1:7006> get name
-> Redirected to slot [5798] located at 127.0.0.1:7002
"andy"
127.0.0.1:7002> 7006位7003的從節點，從上面也是自動跳轉至7002獲取值，這也是redis cluster的特點，它是去中心化，每個節點都是對等的，連線哪個節點都可以獲取和設定資料。
四、叢集節點選舉
現在模擬將7002節點掛掉，按照redis-cluster原理會選舉會將 7002的從節點7005選舉為主節點。
[[email protected] redis-cluster]# ps -ef | grep redis
root 7950 1 0 12:50 ? 00:00:28 ./redis-server 127.0.0.1:7001 [cluster]
root 7952 1 0 12:50 ? 00:00:29 ./redis-server 127.0.0.1:7002 [cluster]
root 7956 1 0 12:50 ? 00:00:29 ./redis-server 127.0.0.1:7003 [cluster]
root 7960 1 0 12:50 ? 00:00:29 ./redis-server 127.0.0.1:7004 [cluster]
root 7964 1 0 12:50 ? 00:00:29 ./redis-server 127.0.0.1:7005 [cluster]
root 7966 1 0 12:50 ? 00:00:29 ./redis-server 127.0.0.1:7006 [cluster]
root 11346 10581 0 14:57 pts/2 00:00:00 grep --color=auto redis
[[email protected] redis-cluster]# kill 7952在檢視叢集中的7002節點
[[email protected] redis-cluster]#
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7002
[ERR] Sorry, can't connect to node 127.0.0.1:7002
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7005
>>> Performing Cluster Check (using node 127.0.0.1:7005)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:5461-10922 (5462 slots) master
0 additional replica(s)
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
1 additional replica(s)
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:0-5460 (5461 slots) master
1 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[[email protected] redis-cluster]# 可以看到叢集連線不了7002節點，而7005有原來的S轉換為M節點，代替了原來的7002節點。我們可以獲取name值：
[[email protected] redis01]# ./redis-cli -c -p 7001
127.0.0.1:7001> get name
-> Redirected to slot [5798] located at 127.0.0.1:7005
"andy"
127.0.0.1:7005>
127.0.0.1:7005> 從7001節點連入，自動跳轉到7005節點，並且獲取name值。
現在我們將7002節點恢復，看是否會自動加入叢集中以及充當的M還是S節點。
[[email protected] redis-cluster]# cd redis02
[[email protected] redis02]# ./redis-server redis.conf
[[email protected] redis02]# 在check一下7002節點
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7002
>>> Performing Cluster Check (using node 127.0.0.1:7002)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
1 additional replica(s)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:5461-10922 (5462 slots) master
1 additional replica(s)
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:0-5460 (5461 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.
[[email protected] redis-cluster]# 五、叢集節點新增
節點新增包括新增主節點、從節點兩種情況。以下分別做一下測試：
1、新增主節點
新增一個節點7007作為主節點修改配置檔案
[[email protected] redis-cluster]# cp -r redis01 redis07
[[email protected] redis-cluster]# cd redis07/
[[email protected] redis07]# sed -i "s/7001/7007/g" ./redis.conf 啟動7007redis服務
[[email protected] redis07]# ./redis-server redis.conf
[[email protected] redis07]# netstat -anp | grep 7007
tcp 0 0 127.0.0.1:17007 0.0.0.0:* LISTEN 13441/./redis-serve
tcp 0 0 127.0.0.1:7007 0.0.0.0:* LISTEN 13441/./redis-serve
[[email protected] redis07]# 上面可以看到，7007已經啟動，現在加入叢集中。新增使用redis-trib.rb的add-node命令
./redis-trib.rb add-node 127.0.0.1:7007 127.0.0.1:7002add-node是加入叢集節點，127.0.0.1:7007為要加入的節點，127.0.0.1:7002 表示加入的叢集的一個節點，用來辨識是哪個叢集，理論上那個叢集的節點都可以。
執行以下add-node
[[email protected] redis-cluster]# ./redis-trib.rb add-node 127.0.0.1:7007 127.0.0.1:7002
>>> Adding node 127.0.0.1:7007 to cluster 127.0.0.1:7002
>>> Performing Cluster Check (using node 127.0.0.1:7002)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
1 additional replica(s)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:5461-10922 (5462 slots) master
1 additional replica(s)
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:0-5460 (5461 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.
>>> Send CLUSTER MEET to node 127.0.0.1:7007 to make it join the cluster.
[OK] New node added correctly.
[[email protected] redis-cluster]# 可以看到7007加入這個Cluster，併成為一個新的節點。
可以check以下7007節點狀態
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7007
>>> Performing Cluster Check (using node 127.0.0.1:7007)
M: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots: (0 slots) master
0 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:0-5460 (5461 slots) master
1 additional replica(s)
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:5461-10922 (5462 slots) master
1 additional replica(s)
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[[email protected] redis-cluster]# M: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots: (0 slots) master
0 additional replica(s)
上面資訊可以看到有4個M節點，3個S節點，7007成為了M主節點，它沒有附屬的從節點，而且Cluster並未給7007分配雜湊卡槽（0 slots）。
可以從客戶端連線叢集檢視一下，叢集節點的連線情況
[[email protected] redis-cluster]# cd redis07/
[[email protected] redis07]# ./redis-cli -c -p 7007
127.0.0.1:7007> cluster nodes
8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006 slave f9886c71e98a53270f7fda961e1c5f730382d48f 0 1462955393326 3 connected
dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001 master - 0 1462955388247 1 connected 0-5460
ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007 myself,master - 0 0 0 connected
f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003 master - 0 1462955390270 3 connected 10923-16383
1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002 slave a5db243087d8bd423b9285fa8513eddee9bb59a6 0 1462955394334 7 connected
a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005 master - 0 1462955392309 7 connected 5461-10922
50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004 slave dd19221c404fb2fc4da37229de56bab755c76f2b 0 1462955389663 1 connected
127.0.0.1:7007> redis-cluster在新增節點時並未分配卡槽，需要我們手動對叢集進行重新分片遷移資料，需要重新分片命令 reshard
redis-trib.rb reshard 127.0.0.1:7005
這個命令是用來遷移slot節點的，後面的127.0.0.1:7005是表示是哪個叢集，埠填［7000-7007］都可以，執行結果如下：
[[email protected] redis-cluster]# ./redis-trib.rb reshard 127.0.0.1:7005
>>> Performing Cluster Check (using node 127.0.0.1:7005)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:5461-10922 (5462 slots) master
1 additional replica(s)
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:10923-16383 (5461 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
M: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots: (0 slots) master
0 additional replica(s)
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:0-5460 (5461 slots) master
1 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
[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)? 它提示我們需要遷移多少slot到7007上，我們平分16384個雜湊槽給4個節點：16384/4 = 4096，我們需要移動4096個槽點到7007上。
[OK] All 16384 slots covered.
How many slots do you want to move (from 1 to 16384)? 4096
What is the receiving node 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: redis-trib 會向你詢問重新分片的源節點（source node），即，要從特點的哪個節點中取出 4096 個雜湊槽，還是從全部節點提取4096個雜湊槽， 並將這些槽移動到7007節點上面。
如果我們不打算從特定的節點上取出指定數量的雜湊槽，那麼可以向redis-trib輸入 all，這樣的話， 叢集中的所有主節點都會成為源節點，redis-trib從各個源節點中各取出一部分雜湊槽，湊夠4096個，然後移動到7007節點上：
Source node #1:all然後開始從別的主節點遷移雜湊槽，並且確認。
Moving slot 1343 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1344 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1345 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1346 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1347 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1348 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1349 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1350 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1351 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1352 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1353 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1354 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1355 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1356 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1357 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1358 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1359 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1360 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1361 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1362 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1363 from dd19221c404fb2fc4da37229de56bab755c76f2b
Moving slot 1364 from dd19221c404fb2fc4da37229de56bab755c76f2b
Do you want to proceed with the proposed reshard plan (yes/no)? yes確認之後，redis-trib就開始執行分片操作，將雜湊槽一個一個從源主節點移動到7007目標主節點。
重新分片結束後我們可以check以下節點的分配情況。
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7001
>>> Performing Cluster Check (using node 127.0.0.1:7001)
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:1365-5460 (4096 slots) master
1 additional replica(s)
M: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots:0-1364,5461-6826,10923-12287 (4096 slots) master
0 additional replica(s)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 slots) master
1 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[[email protected] redis-cluster]# slots:0-1364,5461-6826,10923-12287 (4096 slots) master
可以看到7007節點分片的雜湊槽片不是連續的，間隔的移動。
[[email protected] redis-cluster]# cd redis07/
[[email protected] redis07]# ./redis-cli -c 7007
Could not connect to Redis at 127.0.0.1:6379: Connection refused
[[email protected] redis07]# ./redis-cli -c -p 7007
127.0.0.1:7007> keys *
1) "name"
2) "age"
127.0.0.1:7007>
127.0.0.1:7007> 可以看到將7001的age[741]和name[5798]移動到7007節點上，
主節點7007新增成功。
2、新增從節點
新增一個節點7008節點，使用add-node --slave命令。
[[email protected] redis-cluster]# cp -r redis01/ redis08
[[email protected] redis-cluster]# cd redis08/
[[email protected] redis08]# sed -i "s/7001/7008/g" ./redis.conf
[[email protected] redis08]# ./redis-server redis.conf redis-trib增加從節點的命令為：
./redis-trib.rb add-node --slave --master-id $[nodeid] 127.0.0.1:7008 127.0.0.1:7000nodeid為要加到master主節點的node id，127.0.0.1:7008為新增的從節點，127.0.0.1:7000為叢集的一個節點（叢集的任意節點都行），用來辨識是哪個叢集；如果沒有給定那個主節點--master-id的話，redis-trib將會將新增的從節點隨機到從節點較少的主節點上。
現在我們新增一下7008，看是否會自動加到沒有從節點的7007主節點上。
[[email protected] redis-cluster]# ./redis-trib.rb add-node --slave 127.0.0.1:7008 127.0.0.1:7001>>> Adding node 127.0.0.1:7008 to cluster 127.0.0.1:7001
>>> Performing Cluster Check (using node 127.0.0.1:7001)
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:1365-5460 (4096 slots) master
1 additional replica(s)
M: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots:0-1364,5461-6826,10923-12287 (4096 slots) master
0 additional replica(s)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 slots) master
1 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
Automatically selected master 127.0.0.1:7007
>>> Send CLUSTER MEET to node 127.0.0.1:7008 to make it join the cluster.
Waiting for the cluster to join.
>>> Configure node as replica of 127.0.0.1:7007.
[OK] New node added correctly.
[[email protected] redis-cluster]# 可以看到自動選擇了127.0.0.1:7007為master主節點，並且新增成功。
可以check一下7008：
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7008
>>> Performing Cluster Check (using node 127.0.0.1:7008)
S: 2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 127.0.0.1:7008
slots: (0 slots) slave
replicates ee3efb90e5ac0725f15238a64fc60a18a71205d7
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 slots) master
1 additional replica(s)
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:1365-5460 (4096 slots) master
1 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots:0-1364,5461-6826,10923-12287 (4096 slots) master
1 additional replica(s)
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[[email protected] redis-cluster]# 可以看到7008作為了7007的從節點。
再測試一下指定主節點新增從節點，給7007增加7009從節點。
[[email protected] redis-cluster]# cp -r redis01/ redis09
[[email protected] redis-cluster]# cd redis09
[[email protected] redis09]# sed -i "s/7001/7009/g" ./redis.conf
[[email protected] redis09]# ./redis-server redis.conf 新增7007主節點上
[[email protected] redis-cluster]# ./redis-trib.rb add-node --slave --master-id ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7009 127.0.0.1:7001
>>> Adding node 127.0.0.1:7009 to cluster 127.0.0.1:7001
>>> Performing Cluster Check (using node 127.0.0.1:7001)
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:1365-5460 (4096 slots) master
1 additional replica(s)
S: 2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 127.0.0.1:7008
slots: (0 slots) slave
replicates ee3efb90e5ac0725f15238a64fc60a18a71205d7
M: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots:0-1364,5461-6826,10923-12287 (4096 slots) master
1 additional replica(s)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 slots) master
1 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
>>> Send CLUSTER MEET to node 127.0.0.1:7009 to make it join the cluster.
Waiting for the cluster to join.
>>> Configure node as replica of 127.0.0.1:7007.
[OK] New node added correctly.
[[email protected] redis-cluster]# 顯示從節點7009節點新增到7007主節點，可以看一下7007的從節點，如下：
[[email protected] redis-cluster]# cd ./redis07
[[email protected] redis07]# ./redis-cli -c -p 7007 cluster nodes | grep ee3efb90e5ac0725f15238a64fc60a18a71205d7
1f51443ede952b98724fea2a12f61fe710ab6cb1 127.0.0.1:7009 slave ee3efb90e5ac0725f15238a64fc60a18a71205d7 0 1462962710266 8 connected
ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007 myself,master - 0 0 8 connected 0-1364 5461-6826 10923-12287
2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 127.0.0.1:7008 slave ee3efb90e5ac0725f15238a64fc60a18a71205d7 0 1462962711607 8 connected
[[email protected] redis07]# maser 7007有2個slave 7008,7009。
我們測試一下7007節點掛掉，看7008和7009那個成為主節點。
[[email protected] redis-cluster]# ps -ef | grep redis
root 7950 1 0 12:50 ? 00:02:05 ./redis-server 127.0.0.1:7001 [cluster]
root 7956 1 0 12:50 ? 00:02:11 ./redis-server 127.0.0.1:7003 [cluster]
root 7960 1 0 12:50 ? 00:01:47 ./redis-server 127.0.0.1:7004 [cluster]
root 7964 1 0 12:50 ? 00:02:07 ./redis-server 127.0.0.1:7005 [cluster]
root 7966 1 0 12:50 ? 00:01:46 ./redis-server 127.0.0.1:7006 [cluster]
root 12070 1 0 15:14 ? 00:01:08 ./redis-server 127.0.0.1:7002 [cluster]
root 13441 1 0 16:09 ? 00:01:25 ./redis-server 127.0.0.1:7007 [cluster]
root 15939 1 0 17:41 ? 00:00:20 ./redis-server 127.0.0.1:7008 [cluster]
root 16623 1 0 18:07 ? 00:00:10 ./redis-server 127.0.0.1:7009 [cluster]
root 17295 10581 0 18:37 pts/2 00:00:00 grep --color=auto redis
[[email protected] redis-cluster]# kill -9 13441
[[email protected] redis-cluster]# cd ./redis08
[[email protected] redis08]# ./redis-cli -c -p 7008
127.0.0.1:7008> get name
-> Redirected to slot [5798] located at 127.0.0.1:7009
"andy"
127.0.0.1:7009> cluster nodes
ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007 master,fail - 1462963082317 1462963080194 8 disconnected
50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004 slave dd19221c404fb2fc4da37229de56bab755c76f2b 0 1462963170968 1 connected
f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003 master - 0 1462963168525 3 connected 12288-16383
dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001 master - 0 1462963164466 1 connected 1365-5460
2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 127.0.0.1:7008 slave 1f51443ede952b98724fea2a12f61fe710ab6cb1 0 1462963167508 9 connected
1f51443ede952b98724fea2a12f61fe710ab6cb1 127.0.0.1:7009 myself,master - 0 0 9 connected 0-1364 5461-6826 10923-12287
1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002 slave a5db243087d8bd423b9285fa8513eddee9bb59a6 0 1462963170564 7 connected
8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006 slave f9886c71e98a53270f7fda961e1c5f730382d48f 0 1462963167915 3 connected
a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005 master - 0 1462963169538 7 connected 6827-10922
127.0.0.1:7009> 可以看到7009代替7007成了主節點。
重啟7007之後，會自動變成7009的從節點。
[[email protected] redis-cluster]# cd redis07
[[email protected] redis07]# ./redis-server redis.conf
[[email protected] redis07]# cd ../
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7007
>>> Performing Cluster Check (using node 127.0.0.1:7007)
S: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates dd19221c404fb2fc4da37229de56bab755c76f2b
M: 1f51443ede952b98724fea2a12f61fe710ab6cb1 127.0.0.1:7009
slots:0-1364,5461-6826,10923-12287 (4096 slots) master
2 additional replica(s)
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots:1365-5460 (4096 slots) master
1 additional replica(s)
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
S: 2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 127.0.0.1:7008
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[[email protected] redis-cluster]# 驗證了之前的測試。
六、節點的移除
和節點新增一樣，移除節點也有移除主節點，從節點。
1、移除主節點
移除節點使用redis-trib的del-node命令，
redis-trib del-node 127.0.0.1:7002 ${node-id}127.0.0.1:7002位叢集節點，node-id為要刪除的主節點。 和新增節點不同，移除節點node-id是必需的，測試刪除7001主節點：
[[email protected] redis-cluster]# ./redis-trib.rb del-node 127.0.0.1:7001 <span style="font-size: 14px;">dd19221c404fb2fc4da37229de56bab755c76f2b</span>
>>> Removing node <span style="font-size: 14px;">dd19221c404fb2fc4da37229de56bab755c76f2b</span> from cluster 127.0.0.1:7002
[ERR] Node 127.0.0.1:7001 is not empty! Reshard data away and try again.
[[email protected] redis-cluster]# redis cluster提示7001已經有資料了，不能夠被刪除，需要將他的資料轉移出去，也就是和新增主節點一樣需重新分片。
[[email protected] redis-cluster]# ./redis-trib.rb reshard 127.0.0.1:7002執行以後會提示我們移除的大小，因為7001佔用了4096個槽點
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
How many slots do you want to move (from 1 to 16384)? 輸入4096
提示移動的node id，填寫7009的node id。
How many slots do you want to move (from 1 to 16384)? 4096
What is the receiving node ID? 需要移動到全部主節點上還是單個主節點
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:將4096個槽點移動到7009上，填寫7001的node id ：dd19221c404fb2fc4da37229de56bab755c76f2b
Source node #1:dd19221c404fb2fc4da37229de56bab755c76f2b
Source node #2:done
Do you want to proceed with the proposed reshard plan (yes/no)? yes[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7009
>>> Performing Cluster Check (using node 127.0.0.1:7009)
M: 1f51443ede952b98724fea2a12f61fe710ab6cb1 127.0.0.1:7009
slots:0-6826,10923-12287 (8192 slots) master
3 additional replica(s)
S: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
M: dd19221c404fb2fc4da37229de56bab755c76f2b 127.0.0.1:7001
slots: (0 slots) master
0 additional replica(s)
S: 2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 127.0.0.1:7008
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 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.
[[email protected] redis-cluster]# 可以看到7001有0個卡槽，而7009有8192個卡槽。
在執行移除操作
[[email protected] redis-cluster]# ./redis-trib.rb del-node 127.0.0.1:7002 dd19221c404fb2fc4da37229de56bab755c76f2b
>>> Removing node dd19221c404fb2fc4da37229de56bab755c76f2b from cluster 127.0.0.1:7002
>>> Sending CLUSTER FORGET messages to the cluster...
>>> SHUTDOWN the node.
[[email protected] redis-cluster]# 已經刪除了7001節點。
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7001
[ERR] Sorry, can't connect to node 127.0.0.1:7001
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7009
>>> Performing Cluster Check (using node 127.0.0.1:7009)
M: 1f51443ede952b98724fea2a12f61fe710ab6cb1 127.0.0.1:7009
slots:0-6826,10923-12287 (8192 slots) master
3 additional replica(s)
S: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
S: 2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 127.0.0.1:7008
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 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.
[[email protected] redis-cluster]# 可以看到7001已經連線不了；而7001的從節點7004自動分配到了7009主節點中，7009現在3個從節點。
2、移除從節點
比如刪除7009的7008節點：
[[email protected] redis-cluster]# ./redis-trib.rb del-node 127.0.0.1:7009 2ab1b061c36f30ae35604e9a171ae3afdc3c87e5
>>> Removing node 2ab1b061c36f30ae35604e9a171ae3afdc3c87e5 from cluster 127.0.0.1:7009
>>> Sending CLUSTER FORGET messages to the cluster...
>>> SHUTDOWN the node.
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7008
[ERR] Sorry, can't connect to node 127.0.0.1:7008
[[email protected] redis-cluster]# 刪除從節點比較方便，現在redis-cluster中有3個主節點，4個從節點，如下：
[[email protected] redis-cluster]# ./redis-trib.rb check 127.0.0.1:7009
>>> Performing Cluster Check (using node 127.0.0.1:7009)
M: 1f51443ede952b98724fea2a12f61fe710ab6cb1 127.0.0.1:7009
slots:0-6826,10923-12287 (8192 slots) master
2 additional replica(s)
S: ee3efb90e5ac0725f15238a64fc60a18a71205d7 127.0.0.1:7007
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
S: 50ce1ea59106b4c2c6bc502593a6a7a7dabf5041 127.0.0.1:7004
slots: (0 slots) slave
replicates 1f51443ede952b98724fea2a12f61fe710ab6cb1
M: f9886c71e98a53270f7fda961e1c5f730382d48f 127.0.0.1:7003
slots:12288-16383 (4096 slots) master
1 additional replica(s)
S: 1f07d76585bfab35f91ec711ac53ab4bc00f2d3a 127.0.0.1:7002
slots: (0 slots) slave
replicates a5db243087d8bd423b9285fa8513eddee9bb59a6
S: 8bb3ede48319b46d0015440a91ab277da9353c8b 127.0.0.1:7006
slots: (0 slots) slave
replicates f9886c71e98a53270f7fda961e1c5f730382d48f
M: a5db243087d8bd423b9285fa8513eddee9bb59a6 127.0.0.1:7005
slots:6827-10922 (4096 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.