Redis集群的搭建

一、 redis-cluster架构图

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 集群中内置了 16384 个哈希槽，当需要在 Redis 集群中放置一个 key-value 时，redis 先对 key 使用 crc16 算法算出一个结果，然后把结果对 16384 求余数，这样每个 key 都会对应一个编号在 0-16383 之间的哈希槽，redis 会根据节点数量大致均等的将哈希槽映射到不同的节点
二、redis-cluster投票:容错

(1)领着投票过程是集群中所有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)?
a:如果集群任意master挂掉,且当前master没有slave.集群进入fail状态,也可以理解成集群的slot映射[0-16383]不完成时进入fail状态. ps : redis-3.0.0.rc1加入cluster-require-full-coverage参数,默认关闭,打开集群兼容部分失败.
b: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.
ps: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
三、我们的集群结构

集群中有三个节点的集群，每个节点有一主一备。需要6台虚拟机。
搭建一个伪分布式的集群，使用6个redis实例来模拟。

四、准备搭建集群需要的环境

搭建集群需要使用到官方提供的ruby脚本。
需要安装ruby的环境。
安装ruby

    yum install ruby    yum install rubygems

redis集群管理工具redis-trib.rb

[root@bogon ~]# cd redis-3.0.0[root@bogon redis-3.0.0]# cd src[root@bogon src]# ll *.rb-rwxrwxr-x. 1 root root 48141 Apr  1 07:01 redis-trib.rb[root@bogon src]# 

安装ruby的包：
gem install redis-3.0.0.gem

[root@bogon ~]# gem install redis-3.0.0.gem Successfully installed redis-3.0.01 gem installedInstalling ri documentation for redis-3.0.0...Installing RDoc documentation for redis-3.0.0...

rdb. aof
五、 集群的搭建

第一步：先复制rides 实例 （bin文件）

第二步：修改配置文件端口号 cluster-enabled yes 注释打开

第三步：把创建集群的ruby脚本复制到redis-cluster目录下。
[root@localhost ~]# cp redis-3.0.0/src/*.rb /usr/local/redis-cluster/

第四步启动redis

第五步创建集群
./redis-trib.rb create –replicas 1 192.168.25.153:7001 192.168.25.153:7002 192.168.25.153:7003 192.168.25.153:7004 192.168.25.153:7005 192.168.25.153:7006

[root@bogon redis-cluster]# ./redis-trib.rb create –replicas 1 192.168.25.153:7001 192.168.25.153:7002 192.168.25.153:7003 192.168.25.153:7004 192.168.25.153:7005 192.168.25.153:7006

Creating cluster
Connecting to node 192.168.25.153:7001: OK
Connecting to node 192.168.25.153:7002: OK
Connecting to node 192.168.25.153:7003: OK
Connecting to node 192.168.25.153:7004: OK
Connecting to node 192.168.25.153:7005: OK
Connecting to node 192.168.25.153:7006: OK
Performing hash slots allocation on 6 nodes…
Using 3 masters:
192.168.25.153:7001
192.168.25.153:7002
192.168.25.153:7003
Adding replica 192.168.25.153:7004 to 192.168.25.153:7001
Adding replica 192.168.25.153:7005 to 192.168.25.153:7002
Adding replica 192.168.25.153:7006 to 192.168.25.153:7003
M: 5a8523db7e12ca600dc82901ced06741b3010076 192.168.25.153:7001
slots:0-5460 (5461 slots) master
M: bf6f0929044db485dea9b565bb51e0c917d20a53 192.168.25.153:7002
slots:5461-10922 (5462 slots) master
M: c5e334dc4a53f655cb98fa3c3bdef8a808a693ca 192.168.25.153:7003
slots:10923-16383 (5461 slots) master
S: 2a61b87b49e5b1c84092918fa2467dd70fec115f 192.168.25.153:7004
replicates 5a8523db7e12ca600dc82901ced06741b3010076
S: 14848b8c813766387cfd77229bd2d1ffd6ac8d65 192.168.25.153:7005
replicates bf6f0929044db485dea9b565bb51e0c917d20a53
S: 3192cbe437fe67bbde9062f59d5a77dabcd0d632 192.168.25.153:7006
replicates c5e334dc4a53f655cb98fa3c3bdef8a808a693ca
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 192.168.25.153:7001)
M: 5a8523db7e12ca600dc82901ced06741b3010076 192.168.25.153:7001
slots:0-5460 (5461 slots) master
M: bf6f0929044db485dea9b565bb51e0c917d20a53 192.168.25.153:7002
slots:5461-10922 (5462 slots) master
M: c5e334dc4a53f655cb98fa3c3bdef8a808a693ca 192.168.25.153:7003
slots:10923-16383 (5461 slots) master
M: 2a61b87b49e5b1c84092918fa2467dd70fec115f 192.168.25.153:7004
slots: (0 slots) master
replicates 5a8523db7e12ca600dc82901ced06741b3010076
M: 14848b8c813766387cfd77229bd2d1ffd6ac8d65 192.168.25.153:7005
slots: (0 slots) master
replicates bf6f0929044db485dea9b565bb51e0c917d20a53
M: 3192cbe437fe67bbde9062f59d5a77dabcd0d632 192.168.25.153:7006
slots: (0 slots) master
replicates c5e334dc4a53f655cb98fa3c3bdef8a808a693ca
[OK] All nodes agree about slots configuration.
Check for open slots…
Check slots coverage…
[OK] All 16384 slots covered.
[root@bogon redis-cluster]#

六、测试集群
[root@bogon redis-cluster]# redis01/redis-cli -h 192.168.25.153 -p 7002 -c

[root@bogon redis-cluster]# redis01/redis-cli -h 192.168.25.153 -p 7002
192.168.25.153:7002> set a 100
(error) MOVED 15495 192.168.25.153:7003
192.168.25.153:7002>
[root@bogon redis-cluster]# redis01/redis-cli -h 192.168.25.153 -p 7002 -c
192.168.25.153:7002> set a 100
-> Redirected to slot [15495] located at 192.168.25.153:7003
OK
192.168.25.153:7003>

七、关闭redis
redis01/redis-cli -p 7001 shutdown

八、做启动和关闭脚本

vim startall.sh

cd redis01./redis-server redis.confcd ..cd redis02./redis-server redis.confcd ..cd redis03./redis-server redis.confcd ..cd redis04./redis-server redis.confcd ..cd redis05./redis-server redis.confcd ..cd redis06./redis-server redis.confcd ..

保存 chmod +x startall.sh
关闭脚本同理

redis01/redis-cli -p 7001 shutdownredis02/redis-cli -p 7002 shutdownredis03/redis-cli -p 7003 shutdownredis04/redis-cli -p 7004 shutdownredis05/redis-cli -p 7005 shutdownredis06/redis-cli -p 7006 shutdown