Redis 4 集群搭建

一、概述

1、下载和解包

 cd redis-4.0.1
 make && make install

3、创建redis节点

选择2台服务器，分别为：192.168.59.131，192.168..59.130.每分服务器有3个节点。

先在192.168.59.131创建3个节点：

daemonize    yes                             //redis后台运行
pidfile  /var/run/redis_7000.pid         //pidfile文件对应7000,7002,7003
bind 192.168.59.131                         //绑定ip地址
port  7000                                          //端口7000,7002,7003
cluster-enabled  yes                           //开启集群  把注释#去掉
cluster-config-file  nodes_7000.conf   //集群的配置  配置文件首次启动自动生成 7000,7001,7002
cluster-node-timeout  5000                //请求超时  设置5秒够了
appendonly  yes                          //aof日志开启  有需要就开启，它会每次写操作都记录一条日志

在192.168.59.130创建3个节点：对应的端口改为7003,7004,7005.配置对应的改一下就可以了
4、两台机启动各节点

  ps -ef | grep redis   #查看是否启动成功

 netstat -tnlp | grep redis #可以看到redis监听端口

三、创建集群

前面已经准备好了搭建集群的redis节点，接下来我们要把这些节点都串连起来搭建集群。
官方提供了一个工具：redis-trib.rb(/usr/local/redis-4.0.1/src/redis-trib.rb) 看后缀就知道它是用ruby写的一个程序，所以我们还得安装ruby.

yum -y install ruby ruby-devel rubygems rpm-build

再用 gem 这个命令来安装 redis接口 gem是ruby的一个工具包.

gem install redis
接下来运行一下redis-trib.rb

[root@localhost local]#  /usr/local/redis-4.0.1/src/redis-trib.rb  create  --replicas  1  192.168.59.131:7000 192.168.59.131:7001  192.168.59.131:7003 192.168.59.130:7003  192.168.59.130:7004  192.168.59.130:7005
>>> Creating cluster
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
192.168.59.131:7000
192.168.59.130:7003
192.168.59.131:7001
Adding replica 192.168.59.130:7004 to 192.168.59.131:7000
Adding replica 192.168.59.131:7002 to 192.168.59.130:7003
Adding replica 192.168.59.130:7005 to 192.168.59.131:7001
M: 048937fd4ac542c135e7527f681be12348e8c8d0 192.168.59.131:7000
   slots:0-5460 (5461 slots) master
M: 2039bc32bf55d21d74296cdc91a316022a7afc4b 192.168.59.131:7001
   slots:10923-16383 (5461 slots) master
S: 76514c28d0a40f9751ccaf117d1f8f1d0878475a 192.168.59.131:7002
   replicates a58a304964ff10d10f4323341f7084c9f60f5124
M: a58a304964ff10d10f4323341f7084c9f60f5124 192.168.59.130:7003
   slots:5461-10922 (5462 slots) master
S: 7512d76b416d09619d3b639a94945a676d7b8826 192.168.59.130:7004
   replicates 048937fd4ac542c135e7527f681be12348e8c8d0
S: 7824b9721cb21de60c8d132d668fd3ac5c4eae49 192.168.59.130:7005
   replicates 2039bc32bf55d21d74296cdc91a316022a7afc4b
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 192.168.59.131:7000)
M: 048937fd4ac542c135e7527f681be12348e8c8d0 192.168.59.131:7000
   slots:0-5460 (5461 slots) master
   1 additional replica(s)
S: 76514c28d0a40f9751ccaf117d1f8f1d0878475a 192.168.59.131:7002
   slots: (0 slots) slave
   replicates a58a304964ff10d10f4323341f7084c9f60f5124
M: a58a304964ff10d10f4323341f7084c9f60f5124 192.168.59.130:7003
   slots:5461-10922 (5462 slots) master
   1 additional replica(s)
S: 7512d76b416d09619d3b639a94945a676d7b8826 192.168.59.130:7004
   slots: (0 slots) slave
   replicates 048937fd4ac542c135e7527f681be12348e8c8d0
M: 2039bc32bf55d21d74296cdc91a316022a7afc4b 192.168.59.131:7001
   slots:10923-16383 (5461 slots) master
   1 additional replica(s)
S: 7824b9721cb21de60c8d132d668fd3ac5c4eae49 192.168.59.130:7005
   slots: (0 slots) slave
   replicates 2039bc32bf55d21d74296cdc91a316022a7afc4b
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

到这里集群已经初步搭建好了。

四、测试

1. get 和 set数据
   [root@localhost local]# redis-cli -h 192.168.59.131 -c -p 7002
   192.168.59.131:7002> keys *
   (empty list or set)

[root@localhost local]# redis-cli -h 192.168.59.130 -c -p 7005
192.168.59.130:7005> set hello world
-> Redirected to slot [866] located at 192.168.59.131:7000
OK
192.168.59.131:7000>

[root@localhost local]# redis-cli -h 192.168.59.131 -c -p 7002
192.168.59.131:7002> get hello
-> Redirected to slot [866] located at 192.168.59.131:7000
"world"
192.168.59.131:7000>

2. 模拟故障切换

A. 先把192.168.59.131 其中一个Master服务Down掉，（192.168.59.131有2个Master, 1个Slave） ,
测试一下，依然没有问题，集群依然能继续工作。

[root@localhost script]# /usr/local/redis-4.0.1/src/redis-trib.rb  info  192.168.59.131:7000
192.168.59.130:7003 (a58a3049...) -> 0 keys | 5462 slots | 1 slaves.
192.168.59.130:7005 (7824b972...) -> 0 keys | 5461 slots | 1 slaves.
192.168.59.130:7004 (7512d76b...) -> 0 keys | 5461 slots | 1 slaves.
[OK] 0 keys in 3 masters.
0.00 keys per slot on average.

2. 增加、删除集群节点
   redis-trib.rb add-node ip:port（新增节点） ip:port（现有效节点）
   redis-trib.rb del-node ip:port id（目标节点的id） #删除master节点之前首先要使用reshard移除master的全部slot

3. 重新划分slot
   redis-trib.rb reshard ip:port

[root@localhost script]#  redis-cli -h 192.168.59.130 -c -p 7004
192.168.59.130:7004> cluster replicate 7824b9721cb21de60c8d132d668fd3ac5c4eae49
OK
192.168.59.130:7004> quit

六、深入了解

1. redis-cluster架构图

   
      
   

   　　(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测失效时才生效.
   　　(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

   2. redis-cluster选举容错

      
         
      

      　　(1)领着选举过程是集群中所有master参与,如果半数以上master节点与master节点通信超过(cluster-node-timeout),认为当前master节点挂掉.
      　　(2):什么时候整个集群不可用(cluster_state:fail),当集群不可用时,所有对集群的操作做都不可用，收到((error) CLUSTERDOWN The cluster is down)错误
      　　a:如果集群任意master挂掉,且当前master没有slave.集群进入fail状态,也可以理解成进群的slot映射[0-16383]不完成时进入fail状态.
      　　b:如果进群超过半数以上master挂掉，无论是否有slave集群进入fail状态.

参考：http://www.cnblogs.com/yuanermen/p/5717885.html

作者：WeiminSun
链接：https://www.jianshu.com/p/c8a957413284
来源：简书
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