群集--Redis集群的搭建（实际操作中数据的读写情况，发生故障后的数据读写情况）
文章目录
- 前言
- 一、Redis集群
-
- 1.1 Redis集群介绍
- 1.2 Redis集群的优势
- 1.3 Redis集群的实现方法
- 1.4 Redis-Cluster数据分片
- 1.5 Redis-Cluster的主从复制模型
- 二、Redis集群搭建
-
- 2.1 实验环境
- 2.2 搭建过程
- 2.3 验证集群功能
- 2.4 模拟master服务器宕机情况
- 2.5 总结
前言
上一篇介绍了单节点Redis服务器的搭建，但是单节点Redis服务器会出现的问题：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
此时就需要搭建Redis集群了
一、Redis集群
1.1 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
1.2 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
1.3 Redis集群的实现方法
●客户端分片
●代理分片
●服务器端分片
1.4 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
●节点A包含О到5500号哈希槽
●节点B包含5501到11000号哈希槽
●节点C包含11001到16384号哈希槽
●支持添加或者删除节点
●添加删除节点无需停止服务
例如
●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
●如果想移除节点A，需要将A中的槽移到B和C节点上，再将没有任何槽的A节点从集群中移除
1.5 Redis-Cluster的主从复制模型
●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
●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
●当B和B1都失败后，集群将不可用
二、Redis集群搭建
2.1 实验环境
3台master服务器
192.168.100.100；192.168.100.128；192.168.100.129
3台slave服务器
192.168.100.8；192.168.100.130；192.168.100.131
2.2 搭建过程
安装Redis数据库（6个节点操作一样，详细解释可以看我上次的博客）https://blog.csdn.net/weixin_47151650/article/details/108473001
[root@localhost mnt]# yum install gcc gcc-c++ -y
[root@localhost mnt]# tar zxvf redis-5.0.7.tar.gz -C /opt
[root@localhost mnt]# cd /opt/redis-5.0.7/
[root@localhost redis-5.0.7]# make
[root@localhost redis-5.0.7]# make PREFIX=/usr/local/redis/ install
[root@localhost redis-5.0.7]# cd utils/
[root@localhost utils]# ./install_server.sh
Welcome to the redis service installer
This script will help you easily set up a running redis server
Please select the redis port for this instance: [6379]
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/redis/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/redis/bin/redis-server
Cli Executable : /usr/local/redis/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!
[root@localhost utils]# ln -s /usr/local/redis/bin/ * /usr/local/bin/
[root@localhost utils]# netstat -natp | grep 6379
tcp 0 0 127.0.0.1:6379 0.0.0.0:* LISTEN 24447/redis-server
主从服务器配置文件修改（6个节点都一样）
[root@localhost utils]# vim /etc/redis/6379.conf '前面的是行号'
70 #bind 127.0.0.1 '注释第70行的监听127地址,表示监听所有地址'
89 protected-mode no '去掉第89行注释关闭安全保护'
93 port 6379 '去掉第93行注释,开启端口6379'
137 daemonize yes '去掉第137行注释,以独立进程启动'
700 appendonly yes '去掉第700行注释,开启aof持久化'
833 cluster-enabled yes '去掉第833行注释,开启群集功能'
841 cluster-config-file nodes-6379.conf '去掉第841行注释,群集名称文件设置'
847 cluster-node-timeout 15000 '去掉第847行注释,群集超时时间设置'
[root@localhost utils]# service redis_6379 restart '重启redis服务'
[root@localhost utils]# cd /var/lib/redis/6379/
[root@localhost 6379]# ls
appendonly.aof dump.rdb nodes-6379.conf
'生成了三个文件，appendonly.aof是AOF持久化文件，dump.rdb是RDB快照文件，nodes-6379.conf是节点首次启动生成的配置文件'
主服务器安装rvm，RUBY控制集群软件
[root@master01 6379]# gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
'导入key文件，若出现error，重新导入一次即可'
[root@master01 6379]# curl -sSL https://get.rvm.io | bash -s stable '安装rvm'
[root@master01 opt]# ./rvm-installer.sh
[root@master01 opt]# source /etc/profile.d/rvm.sh '执行环境变量'
[root@master01 opt]# rvm list known '列出ruby可以安装的版本'
# MRI Rubies
[ruby-]1.8.6[-p420]
[ruby-]1.8.7[-head] # security released on head
[ruby-]1.9.1[-p431]
[ruby-]1.9.2[-p330]
[ruby-]1.9.3[-p551]
[ruby-]2.0.0[-p648]
[ruby-]2.1[.10]
[ruby-]2.2[.10]
[ruby-]2.3[.8]
[ruby-]2.4[.10]
[ruby-]2.5[.8]
[ruby-]2.6[.6]
[ruby-]2.7[.1]
ruby-head
[root@master01 opt]# rvm install 2.4.10 '安装ruby2.4.10版本，安装版本的事件会比较长'
[root@master01 opt]# ruby -v '查看当前ruby版本'
ruby 2.4.10p364 (2020-03-31 revision 67879) [x86_64-linux]
[root@master01 opt]# rvm use 2.4.10 '使用Ruby2.4.10版本'
Using /usr/local/rvm/gems/ruby-2.4.10
[root@master01 opt]# gem install redis '再次安装Redis'
Fetching redis-4.2.2.gem
Successfully installed redis-4.2.2
Parsing documentation for redis-4.2.2
Installing ri documentation for redis-4.2.2
Done installing documentation for redis after 0 seconds
1 gem installed
主服务器上创建群集
[root@localhost profile.d]# redis-cli --cluster create 192.168.100.100:6379 192.168.100.128:6379 192.168.100.129:6379 192.168.100.8:6379 192.168.100.130:6379 192.168.100.131:6379 --cluster-replicas 1
>>> Performing hash slots allocation on 6 nodes...
Master[0] -> Slots 0 - 5460
Master[1] -> Slots 5461 - 10922
Master[2] -> Slots 10923 - 16383
Adding replica 192.168.100.130:6379 to 192.168.100.100:6379
Adding replica 192.168.100.131:6379 to 192.168.100.128:6379
Adding replica 192.168.100.8:6379 to 192.168.100.129:6379
M: 1daf95d3008b5a070c698a677ff14271630c90b6 192.168.100.100:6379
slots:[0-16383] (5461 slots) master
M: 1daf95d3008b5a070c698a677ff14271630c90b6 192.168.100.128:6379
slots:[0-16383] (5462 slots) master
M: 1daf95d3008b5a070c698a677ff14271630c90b6 192.168.100.129:6379
slots:[0-16383] (5461 slots) master
S: 1d51bf7d5e95b14216c0d2f7a448c97c815f7895 192.168.100.8:6379
replicates 1daf95d3008b5a070c698a677ff14271630c90b6
S: 1d51bf7d5e95b14216c0d2f7a448c97c815f7895 192.168.100.130:6379
replicates 1daf95d3008b5a070c698a677ff14271630c90b6
S: 1d51bf7d5e95b14216c0d2f7a448c97c815f7895 192.168.100.131:6379
replicates 1daf95d3008b5a070c698a677ff14271630c90b6
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 192.168.100.100:6379)
M: 1daf95d3008b5a070c698a677ff14271630c90b6 192.168.100.100:6379
slots:[0-16383] (16384 slots) master
1 additional replica(s)
S: 1d51bf7d5e95b14216c0d2f7a448c97c815f7895 192.168.100.8:6379
slots: (0 slots) slave
replicates 1daf95d3008b5a070c698a677ff14271630c90b6
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
2.3 验证集群功能
[root@master01 ~]# redis-cli -c -h 192.168.100.100 '连接master01'
192.168.100.100:6379> keys *
(empty list or set)
192.168.100.100:6379> set name zhangsan '创建一个键值'
-> Redirected to slot [5798] located at 192.168.100.128:6379 '存入master02'
OK
192.168.100.128:6379> set addr nanjing '自动跳转至master02，再创建一个键值'
-> Redirected to slot [12790] located at 192.168.100.129:6379 '存入master03'
OK
[root@slave03 6379]# redis-cli -c -h 192.168.100.130 '进入master02的slave'
192.168.100.130:6379> keys * '查看键值，发现已同步'
1) "name"
192.168.100.130:6379> get name
-> Redirected to slot [5798] located at 192.168.100.129:6379 '在master02找到'
"zhangsan"
[root@slave01 6379]# redis-cli -c -h 192.168.100.131 '进入master03的slave'
192.168.100.131:6379> keys * '查看键值，发现已同步'
1) "addr"
192.168.100.131:6379> get addr
-> Redirected to slot [12790] located at 192.168.100.129:6379 '在master03找到'
"nanjing"
2.4 模拟master服务器宕机情况
[root@master03 6379]# service redis_6379 stop '关闭master03'
Stopping ...
Waiting for Redis to shutdown ...
Redis stopped
[root@slave01 6379]# redis-cli -c -h 192.168.100.131 '连接master03的slave'
192.168.100.131:6379> keys * '依旧可以查看键值，业务不受影响'
1) "addr"
192.168.100.131:6379> get addr
"nanjing"
[root@master02 ~]# redis-cli -c -h 192.168.100.128 '进入master02'
192.168.100.100:6379> set age 20 '创建一个键值，存入了master01'
-> Redirected to slot [741] located at 192.168.100.128:6379
OK
192.168.179.124:6379> set team yun '再创建一个键值，此时存入了master03的slave'
-> Redirected to slot [15631] located at 192.168.179.126:6379
OK
192.168.100.131:6379> keys * '查看master03的slave，两个键值存在'
1) "team"
2) "addr"
192.168.100.131:6379> get team '刚刚创建的键值正常查看'
"yun"
2.5 总结
在Redis集群中，3个master之间依次写入数据，分别在各自的slave中复制一份数据，在一台master宕机后，由它的slave顶替进行数据的读写工作