【图文解析 】Redis集群，重要！重要！！重要！！！

redis-cluster架构图

 

 

 

 

 

 

 

 

 

 

 

 

 

 

架构细节：

1. 所有的redis节点彼此互联（PING-PONG机制），内部使用二进制协议优化传输速度和带宽；
2. 节点的fail是通过集群中超过半数的节点检查失效时才生效；
3. 客户端与redis节点直连，不需要中间proxy层，客户端不需要连接集群所有的节点，连接集群中任何一个可用节点即可；

4. redis-cluster把所有的物理节点映射到[0-16383]slot上,cluster 负责维护

node<->slot<->value

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

redis-cluster投票:容错

 

 

 

 

 

 

 

 

 

 

 

 

1. 集群中所有master参与投票,如果半数以上master节点与其中一个master节点通信超过(cluster-node-timeout),认为该master节点挂掉.
2. 什么时候整个集群不可用(cluster_state:fail)? 

• 如果集群任意master挂掉,且当前master没有slave，则集群进入fail状态。也可以理解成集群的[0-16383]slot映射不完全时进入fail状态。
• 如果集群超过半数以上master挂掉，无论是否有slave，集群进入fail状态。

 

 

安装ruby

1. 集群管理工具（redis-trib.rb）是使用ruby脚本语言编写的。

第一步：安装ruby

[root@itheima bin2]# yum install ruby

[root@itheima bin2]# yum install rubygems

第二步：将以下文件上传到linux系统

第三步：安装ruby和redis接口

[root@itheima ~]# gem install redis-3.0.0.gem

第四步：将redis-3.0.0包下src目录中的以下文件拷贝到redis19/redis-cluster/

[root@itheima src]# cd /usr/local/redis19/

[root@itheima redis19]# mkdir redis-cluster

[root@itheima redis19]# cd /root/redis-3.0.0/src/

[root@itheima src]# cp redis-trib.rb  /usr/local/redis19/redis-cluster

第五步：查看是否拷贝成功

 

搭建集群

1. 搭建集群最少也得需要3台主机，如果每台主机再配置一台从机的话，则最少需要6台机器。

端口设计如下：7001-7006

第一步：复制出一个7001机器

[root@itheima redis19]# cp bin ./redis-cluster/7001 –r

第二步：如果存在持久化文件，则删除

[root@itheima 7001]# rm -rf appendonly.aof dump.rdb

第三步：设置集群参数

第四步：修改端口

第五步：复制出7002-7006机器

[root@itheima redis-cluster]# cp 7001/ 7002 -r

[root@itheima redis-cluster]# cp 7001/ 7003 -r

[root@itheima redis-cluster]# cp 7001/ 7004 -r

[root@itheima redis-cluster]# cp 7001/ 7005 -r

[root@itheima redis-cluster]# cp 7001/ 7006 –r

第六步：修改7002-7006机器的端口

第七步：启动7001-7006这六台机器

第八步：修改start-all.sh文件的权限

[root@itheima redis-cluster]# chmod u+x start-all.sh

[root@itheima redis-cluster]# ./start-all.sh

第九步：创建集群

[root@itheima redis-cluster]# ./redis-trib.rb create --replicas 1 192.168.242.137:7001 192.168.242.137:7002 192.168.242.137:7003 192.168.242.137:7004 192.168.242.137:7005  192.168.242.137:7006 >>> Creating cluster Connecting to node 192.168.242.137:7001: OK Connecting to node 192.168.242.137:7002: OK Connecting to node 192.168.242.137:7003: OK Connecting to node 192.168.242.137:7004: OK Connecting to node 192.168.242.137:7005: OK Connecting to node 192.168.242.137:7006: OK >>> Performing hash slots allocation on 6 nodes... Using 3 masters: 192.168.242.137:7001 192.168.242.137:7002 192.168.242.137:7003 Adding replica 192.168.242.137:7004 to 192.168.242.137:7001 Adding replica 192.168.242.137:7005 to 192.168.242.137:7002 Adding replica 192.168.242.137:7006 to 192.168.242.137:7003 M: 8240cd0fe6d6f842faa42b0174fe7c5ddcf7ae24 192.168.242.137:7001    slots:0-5460 (5461 slots) master M: 4f52a974f64343fd9f1ee0388490b3c0647a4db7 192.168.242.137:7002    slots:5461-10922 (5462 slots) master M: cb7c5def8f61df2016b38972396a8d1f349208c2 192.168.242.137:7003    slots:10923-16383 (5461 slots) master S: 66adf006fed43b3b5e499ce2ff1949a756504a16 192.168.242.137:7004    replicates 8240cd0fe6d6f842faa42b0174fe7c5ddcf7ae24 S: cbb0c9bc4b27dd85511a7ef2d01bec90e692793b 192.168.242.137:7005    replicates 4f52a974f64343fd9f1ee0388490b3c0647a4db7 S: a908736eadd1cd06e86fdff8b2749a6f46b38c00 192.168.242.137:7006    replicates cb7c5def8f61df2016b38972396a8d1f349208c2 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 192.168.242.137:7001) M: 8240cd0fe6d6f842faa42b0174fe7c5ddcf7ae24 192.168.242.137:7001    slots:0-5460 (5461 slots) master M: 4f52a974f64343fd9f1ee0388490b3c0647a4db7 192.168.242.137:7002    slots:5461-10922 (5462 slots) master M: cb7c5def8f61df2016b38972396a8d1f349208c2 192.168.242.137:7003    slots:10923-16383 (5461 slots) master M: 66adf006fed43b3b5e499ce2ff1949a756504a16 192.168.242.137:7004    slots: (0 slots) master    replicates 8240cd0fe6d6f842faa42b0174fe7c5ddcf7ae24 M: cbb0c9bc4b27dd85511a7ef2d01bec90e692793b 192.168.242.137:7005    slots: (0 slots) master    replicates 4f52a974f64343fd9f1ee0388490b3c0647a4db7 M: a908736eadd1cd06e86fdff8b2749a6f46b38c00 192.168.242.137:7006    slots: (0 slots) master    replicates cb7c5def8f61df2016b38972396a8d1f349208c2 [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. [root@itheima redis-cluster]#

 

连接集群

[root@itheima 7001]# ./redis-cli -h 192.168.242.137 -p 7001 –c

-c：指定是集群连接

1. 查看集群信息
2. 查看集群信息

192.168.242.137:7002> cluster info cluster_state:ok cluster_slots_assigned:16384 cluster_slots_ok:16384 cluster_slots_pfail:0 cluster_slots_fail:0 cluster_known_nodes:6 cluster_size:3 cluster_current_epoch:6 cluster_my_epoch:2 cluster_stats_messages_sent:2372 cluster_stats_messages_received:2372 192.168.242.137:7002>

      3.查看集群节点

192.168.242.137:7002> cluster nodes 8240cd0fe6d6f842faa42b0174fe7c5ddcf7ae24 192.168.242.137:7001 master - 0 1451581348093 1 connected 0-5460 cb7c5def8f61df2016b38972396a8d1f349208c2 192.168.242.137:7003 master - 0 1451581344062 3 connected 10923-16383 66adf006fed43b3b5e499ce2ff1949a756504a16 192.168.242.137:7004 slave 8240cd0fe6d6f842faa42b0174fe7c5ddcf7ae24 0 1451581351115 1 connected a908736eadd1cd06e86fdff8b2749a6f46b38c00 192.168.242.137:7006 slave cb7c5def8f61df2016b38972396a8d1f349208c2 0 1451581349101 3 connected 4f52a974f64343fd9f1ee0388490b3c0647a4db7 192.168.242.137:7002 myself,master - 0 0 2 connected 5461-10922 cbb0c9bc4b27dd85511a7ef2d01bec90e692793b 192.168.242.137:7005 slave 4f52a974f64343fd9f1ee0388490b3c0647a4db7 0 1451581350108 5 connected