NoSQL之Redis集群搭建
一、案例概述
1、单节点Redis服务器带来的问题
·单点故障，服务不可用
·无法处理大量的并发数据请求
·数据丢失——大灾难
2、解决方法
搭建Redis集群
二、案例前置知识点
1、Redis集群介绍
·Redis集群是一个提供在多个Redis间节点间共享数据的程序集
·Redis集群并不支持处理多个keys的命令，因为这需要在不同的节点间移动数据，从而达不到像Redis那样的性能，在高负载的情况下可能会导致不可预料的错误
·Redis集群通过分区来提供一定程度的可用性，在实际环境中当某个节点宕机或者不可达的情况下可继续处理命令
2、Redis集群的优势
·自动分割数据到不同的节点上
·整个集群的部分节点失败或者不可达的情况下能够继续处理命令
3、Redis集群的实现方法
·有客户端分片
·代理分片
·服务器端分片
4、Redis-Cluster数据分片
·Redis集群没有使用一致性hash，而是引入了哈希槽概念
·Redis集群有16384个哈希槽
·每个key通过CRC16校验后对16384取模来决定放置槽
·集群的每个节点负责一部分哈希槽
·以3个节点组成的集群为例
①节点A包含0到5500号哈希槽
②节点B包含5501到11000号哈希槽
③节点C包含11001到16384号哈希槽
·支持添加或者删除节点
①添加删除节点无需停止服务
②例如：
1）如果想新添加个节点D，需要移动节点A、B、C中的部分槽到D上
2）如果想移除节点A，需要将A中的槽移到B和C上，再将没有任何槽的A节点从集群中移除
·Redis-Cluster的主从复制模型
①集群中具有A，B，C三个节点，如果节点B失败了，整个集群就会因缺少5501-11000这个范围的槽而不可用
②为每个节点添加一个从节点A1，B1，C1，整个集群便有三个master节点和三个slave节点组成，在节点B失败后，集群便会选举B1为新的主节点继续服务
③当B和B1都失败后，集群将不可用
三、Redis集群搭建
1、案例拓扑图
2、环境
|
Master1服务器 |
20.0.0.10 |
|
Master2服务器 |
20.0.0.20 |
|
Master3服务器 |
20.0.0.30 |
|
Slave1服务器 |
20.0.0.40 |
|
Slave2服务器 |
20.0.0.50 |
|
Slave3服务器 |
20.0.0.60 |
3、安装Redis
所有服务器上都需要安装，只在master1上演示,其他安装都一样
[root@master1 ~]# cd redis-5.0.7/
[root@master1 redis-5.0.7]# make -j2
[root@master1 redis-5.0.7]# make PREFIX=/usr/local/redis install
[root@master1 redis-5.0.7]# ln -s /usr/local/redis/bin/* /usr/local/bin/
[root@master1 redis-5.0.7]# cd utils/
[root@master1 utils]# ./install_server.sh
Welcome to the redis service installer
This script will help you easily set up a running redis server
Selecting default: 6379
Please select the redis config file name [/etc/redis/6379.conf]
Selected default - /etc/redis/6379.conf
Please select the redis log file name [/var/log/redis_6379.log]
Selected default - /var/log/redis_6379.log
Please select the data directory for this instance [/var/lib/redis/6379]
Selected default - /var/lib/redis/6379
Please select the redis executable path [/usr/local/bin/redis-server]
Selected config:
Port : 6379
Config file : /etc/redis/6379.conf
Log file : /var/log/redis_6379.log
Data dir : /var/lib/redis/6379
Executable : /usr/local/bin/redis-server
Cli Executable : /usr/local/bin/redis-cli
Is this ok? Then press ENTER to go on or Ctrl-C to abort.
Copied /tmp/6379.conf => /etc/init.d/redis_6379
Installing service...
Successfully added to chkconfig!
Successfully added to runlevels 345!
Starting Redis server...
Installation successful!
所有服务器上都需要修改，只在master1上演示
bind 20.0.0.10 #删除原来的127.0.0.1，改成自己的IP
所有服务器上都需要开启，只在master1上演示
[root@master1 utils]# /etc/init.d/redis_6379 restart
Stopping ...
Waiting for Redis to shutdown ...
Redis stopped
Starting Redis server...
[root@master1 utils]# netstat -anpt | grep 6379
tcp 0 0 20.0.0.10:6379 0.0.0.0:* LISTEN 18943/redis-server
tcp 0 0 20.0.0.10:16379 0.0.0.0:* LISTEN 18943/redis-server
6、在master1上使用脚本创建集群
gem是ruby写的软件包。rubygems是用来打包、下载、安装、使用gem软件包的工具。要搭建集群的话，需要使用一个工具（脚本文件），这个工具在redis解压文件的源代码里。因为这个工具是一个ruby脚本文件，所以这个工具的运行需要ruby的运行环境，就相当于java语言的运行需要在jvm上。所以需要安装ruby。
[root@master1 utils]# yum -y install ruby rubygems 1 [root@master1 utils]# cd
[root@master1 ~]# gem install redis-3.2.0.gem
Successfully installed redis-3.2.0
Parsing documentation for redis-3.2.0
Installing ri documentation for redis-3.2.0
1 gem installed
[root@master1 ~]# cd redis-5.0.7/src/
[root@master1 src]# redis-cli --cluster create --cluster-replicas 1 20.0.0.10:6379 20.0.0.20:6379 20.0.0.30:6379 20.0.0.40:6379 20.0.0.50:6379 20.0.0.60:6379
>>> Performing hash slots allocation on 6 nodes...
Master[0] -> Slots 0 - 5460
Master[1] -> Slots 5461 - 10922
Master[2] -> Slots 10923 - 16383
Adding replica 20.0.0.50:6379 to 20.0.0.10:6379
Adding replica 20.0.0.60:6379 to 20.0.0.20:6379
Adding replica 20.0.0.40:6379 to 20.0.0.30:6379
M: 7ae810725eb6ff5d3c8b222dff08bed993f7738f 20.0.0.10:6379
slots:[0-5460] (5461 slots) master
M: 0229fcffb856fac03854aebcc053ff4115a8b248 20.0.0.20:6379
slots:[5461-10922] (5462 slots) master
M: d29fc5dcf1765ff01adc89aae5ec27131d05d311 20.0.0.30:6379
slots:[10923-16383] (5461 slots) master
S: bb00f5e1da389a397580abdeec8bfab15cf2b404 20.0.0.40:6379
replicates d29fc5dcf1765ff01adc89aae5ec27131d05d311
S: f1843f0b57222c396f8c72acbbe5a31bffdfe790 20.0.0.50:6379
replicates 7ae810725eb6ff5d3c8b222dff08bed993f7738f
S: 7316d95a643a9ffd439e37d248ff354c69cdea0b 20.0.0.60:6379
replicates 0229fcffb856fac03854aebcc053ff4115a8b248
Can I set the above configuration? (type 'yes' to accept): yes #输入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 20.0.0.10:6379)
M: 7ae810725eb6ff5d3c8b222dff08bed993f7738f 20.0.0.10:6379
slots:[0-5460] (5461 slots) master
1 additional replica(s)
M: 0229fcffb856fac03854aebcc053ff4115a8b248 20.0.0.20:6379
slots:[5461-10922] (5462 slots) master
1 additional replica(s)
M: d29fc5dcf1765ff01adc89aae5ec27131d05d311 20.0.0.30:6379
slots:[10923-16383] (5461 slots) master
1 additional replica(s)
S: 7316d95a643a9ffd439e37d248ff354c69cdea0b 20.0.0.60:6379
slots: (0 slots) slave
replicates 0229fcffb856fac03854aebcc053ff4115a8b248
S: f1843f0b57222c396f8c72acbbe5a31bffdfe790 20.0.0.50:6379
slots: (0 slots) slave
replicates 7ae810725eb6ff5d3c8b222dff08bed993f7738f
S: bb00f5e1da389a397580abdeec8bfab15cf2b404 20.0.0.40:6379
slots: (0 slots) slave
replicates d29fc5dcf1765ff01adc89aae5ec27131d05d311
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
7、测试群集
[root@master1 src]# redis-cli -h 20.0.0.10 -p 6379 -c
20.0.0.10:6379> set centos 7.6
OK
20.0.0.10:6379> quit
[root@master1 src]# redis-cli -h 20.0.0.20 -p 6379 -c
20.0.0.20:6379> get centos
-> Redirected to slot [467] located at 20.0.0.10:6379
"7.6"
20.0.0.10:6379> quit
[root@master1 src]# redis-cli -h 20.0.0.50 -p 6379 -c
20.0.0.50:6379> get centos
-> Redirected to slot [467] located at 20.0.0.10:6379
"7.6"
20.0.0.10:6379> cluster info #查看集群状态
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:1
cluster_stats_messages_ping_sent:383
cluster_stats_messages_pong_sent:373
cluster_stats_messages_sent:756
cluster_stats_messages_ping_received:368
cluster_stats_messages_pong_received:383
cluster_stats_messages_meet_received:5
cluster_stats_messages_received:756
20.0.0.10:6379> cluster nodes #查看节点信息
0229fcffb856fac03854aebcc053ff4115a8b248 20.0.0.20:6379@16379 master - 0 1605018468897 2 connected 5461-10922
d29fc5dcf1765ff01adc89aae5ec27131d05d311 20.0.0.30:6379@16379 master - 0 1605018466000 3 connected 10923-16383
7316d95a643a9ffd439e37d248ff354c69cdea0b 20.0.0.60:6379@16379 slave 0229fcffb856fac03854aebcc053ff4115a8b248 0 1605018467000 6 connected
7ae810725eb6ff5d3c8b222dff08bed993f7738f 20.0.0.10:6379@16379 myself,master - 0 1605018465000 1 connected 0-5460
f1843f0b57222c396f8c72acbbe5a31bffdfe790 20.0.0.50:6379@16379 slave 7ae810725eb6ff5d3c8b222dff08bed993f7738f 0 1605018467876 5 connected
bb00f5e1da389a397580abdeec8bfab15cf2b404 20.0.0.40:6379@16379 slave d29fc5dcf1765ff01adc89aae5ec27131d05d311 0 1605018468000 4 connected
