目录
1、什么是集群
2、为什么使用
3、集群连接
4、redis cluster 如何分配这六个节点?
5、集群搭建:
1、什么是集群
- Redis 集群(包括很多小集群)实现了对Redis的水平扩容,即启动N个redis节点,将整个数据库分布存储在这N个节点中,每个节点存储总数据的1/N,即一个小集群存储1/N的数据,每个小集群里面维护好自己的1/N的数据。
- Redis 集群通过分区(partition)来提供一定程度的可用性(availability): 即使集群中有一部分节点失效或者无法进行通讯, 集群也可以继续处理命令请求。
- 该模式的redis集群特点是:分治、分片。
2、为什么使用
容量不够,redis如何进行扩容?
并发写操作, redis如何分摊?
另外,主从模式,薪火相传模式,主机宕机,导致ip地址发生变化,应用程序中配置需要修改对应的主机地址、端口等信息。
之前通过代理主机来解决,但是redis3.0中提供了解决方案。就是无中心化集群配置。
3、集群连接
- 普通方式登录:可能直接进入读主机,存储数据时,会出现MOVED重定向操作,所以,应该以集群方式登录。
- 集群登录:redis-cli -c -p 6379 采用集群策略连接,设置数据会自动切换到相应的写主机。
4、redis cluster 如何分配这六个节点?
一个集群至少要有三个主节点。
选项 –cluster-replicas 1 :表示我们希望为集群中的每个主节点创建一个从节点。
分配原则尽量保证每个主数据库运行在不同的IP地址,每个从库和主库不在一个IP地址上。
5、集群搭建:
1) 通过redis中utils路径下 ./install_server.sh 执行文件创建6个不同的redis节点,端口号分别为6379、6380、6381、8362、6383、6384
2)如果各个节点原本有存储数据,则先将各个节点的数据文件清空。将6个文件夹内的文件全部删除。
清空数据目录。删除 Redis 数据目录下的所有文件。使用命令: rm -rf /path/to/redis/data/*
3)修改6个redis节点的配置文件
在 /etc/redis 文件中,找到每一个端口号对应的配置文件:
例如修改的内容如下:
bind 0.0.0.0
port 6380 # 设置成对应服务专属的端口号
daemonize yes
dbfilename "dump6380.rdb" # 设置成对应服务专属的名字
appendonly yes
cluster-enabled yes
cluster-config-file nodes-6380.conf # 设置成对应服务专属的
4)启动六个节点
[root@bogon src]# ./redis-server /etc/redis/6379.conf
[root@bogon src]# ./redis-server /etc/redis/6380.conf
[root@bogon src]# ./redis-server /etc/redis/6381.conf
[root@bogon src]# ./redis-server /etc/redis/6382.conf
[root@bogon src]# ./redis-server /etc/redis/6383.conf
[root@bogon src]# ./redis-server /etc/redis/6384.conf
5)查看各个节点是否启动成功
[root@bogon src]# ps -ef | grep redis
root 3889 1 0 09:56 ? 00:00:03 ./redis-server 0.0.0.0:6379 [cluster]
root 3895 1 0 09:56 ? 00:00:03 ./redis-server 0.0.0.0:6380 [cluster]
root 3901 1 0 09:57 ? 00:00:03 ./redis-server 0.0.0.0:6381 [cluster]
root 3907 1 0 09:57 ? 00:00:02 ./redis-server *:6382 [cluster]
root 3913 1 0 09:57 ? 00:00:02 ./redis-server 0.0.0.0:6383 [cluster]
root 3919 1 0 09:57 ? 00:00:02 ./redis-server 0.0.0.0:6384 [cluster]
root 4247 2418 0 10:22 pts/0 00:00:00 grep --color=auto redis
6)配置集群
命令格式: --cluster-replicas 1 表示为每个master创建一个slave节点
注意:这里的IP为每个节点所在机器的真实IP
[root@localhost src]# ./redis-cli --cluster create 192.168.177.128:6379 192.168.177.128:6380 192.168.177.128:6381 192.168.177.128:6382 192.168.177.128:6383 192.168.177.128:6384 --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 192.168.177.128:6383 to 192.168.177.128:6379
Adding replica 192.168.177.128:6384 to 192.168.177.128:6380
Adding replica 192.168.177.128:6382 to 192.168.177.128:6381
>>> Trying to optimize slaves allocation for anti-affinity
[WARNING] Some slaves are in the same host as their master
M: ae77569d28f01657d9e3e04810e8562abdb3f5dd 192.168.177.128:6379
slots:[0-5460] (5461 slots) master
M: 5ccafb9ee2f223c987c740d3d8282f200e4892dd 192.168.177.128:6380
slots:[5461-10922] (5462 slots) master
M: dcd5d5066cd9aa5e3f2830ce985395acb978d764 192.168.177.128:6381
slots:[10923-16383] (5461 slots) master
S: 8849bb5437931a3fd8510ffa4c0f755f4e26d1eb 192.168.177.128:6382
replicates ae77569d28f01657d9e3e04810e8562abdb3f5dd
S: b00800f65775c52519bd6e9f398f916ffe46fed8 192.168.177.128:6383
replicates 5ccafb9ee2f223c987c740d3d8282f200e4892dd
S: 6e7a1ae63691267b000363f6528b620a656e03e7 192.168.177.128:6384
replicates dcd5d5066cd9aa5e3f2830ce985395acb978d764
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 192.168.177.128:6379)
M: ae77569d28f01657d9e3e04810e8562abdb3f5dd 192.168.177.128:6379
slots:[0-5460] (5461 slots) master
1 additional replica(s)
M: dcd5d5066cd9aa5e3f2830ce985395acb978d764 192.168.177.128:6381
slots:[10923-16383] (5461 slots) master
1 additional replica(s)
M: 5ccafb9ee2f223c987c740d3d8282f200e4892dd 192.168.177.128:6380
slots:[5461-10922] (5462 slots) master
1 additional replica(s)
S: 8849bb5437931a3fd8510ffa4c0f755f4e26d1eb 192.168.177.128:6382
slots: (0 slots) slave
replicates ae77569d28f01657d9e3e04810e8562abdb3f5dd
S: b00800f65775c52519bd6e9f398f916ffe46fed8 192.168.177.128:6383
slots: (0 slots) slave
replicates 5ccafb9ee2f223c987c740d3d8282f200e4892dd
S: 6e7a1ae63691267b000363f6528b620a656e03e7 192.168.177.128:6384
slots: (0 slots) slave
replicates dcd5d5066cd9aa5e3f2830ce985395acb978d764
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
7)查看主从关系
命令格式:redis-cli --cluster check 【本台redis自己的IP】:【本台redis自己的端口】
[root@localhost src]# ./redis-cli --cluster check 192.168.177.128:6379
192.168.177.128:6379 (ae77569d...) -> 0 keys | 5461 slots | 1 slaves.
192.168.177.128:6381 (dcd5d506...) -> 0 keys | 5461 slots | 1 slaves.
192.168.177.128:6380 (5ccafb9e...) -> 0 keys | 5462 slots | 1 slaves.
[OK] 0 keys in 3 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.177.128:6379)
M: ae77569d28f01657d9e3e04810e8562abdb3f5dd 192.168.177.128:6379
slots:[0-5460] (5461 slots) master
1 additional replica(s)
M: dcd5d5066cd9aa5e3f2830ce985395acb978d764 192.168.177.128:6381
slots:[10923-16383] (5461 slots) master
1 additional replica(s)
M: 5ccafb9ee2f223c987c740d3d8282f200e4892dd 192.168.177.128:6380
slots:[5461-10922] (5462 slots) master
1 additional replica(s)
S: 8849bb5437931a3fd8510ffa4c0f755f4e26d1eb 192.168.177.128:6382
slots: (0 slots) slave
replicates ae77569d28f01657d9e3e04810e8562abdb3f5dd
S: b00800f65775c52519bd6e9f398f916ffe46fed8 192.168.177.128:6383
slots: (0 slots) slave
replicates 5ccafb9ee2f223c987c740d3d8282f200e4892dd
S: 6e7a1ae63691267b000363f6528b620a656e03e7 192.168.177.128:6384
slots: (0 slots) slave
replicates dcd5d5066cd9aa5e3f2830ce985395acb978d764
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
查看下图即可发现,一主对一从:
8) 主节点数据写测试
加参数 -c ,防止路由失效
[root@bogon src]# ./redis-cli -p 6381 -c
127.0.0.1:6381> get name
-> Redirected to slot [5798] located at 192.168.109.149:6380
(nil)
192.168.109.149:6380> get name
(nil)
192.168.109.149:6380>
9)从节点读数据测试
情况:redis cluster集群中slave节点能成功复制master节点数据槽数据,但是无法get数据,显示只能到对应的master节点读取
原因:Redis Cluster集群中的从节点,官方默认设置的是不分担读请求的、只作备份和故障转移用,当有请求读向从节点时,会被重定向对应的主节点来处理
解决办法:在get数据之前先使用命令readonly,这个readonly告诉 Redis Cluster 从节点客户端愿意读取可能过时的数据并且对写请求不感兴趣文章来源:https://www.toymoban.com/news/detail-614761.html
注意:断开连接后readonly就失效了,再次连接需要重新使用该命令。文章来源地址https://www.toymoban.com/news/detail-614761.html
[root@bogon src]# ./redis-cli -p 6379 -c
127.0.0.1:6379> set name zhangsan
-> Redirected to slot [5798] located at 192.168.109.149:6380
OK
192.168.109.149:6380> get name
"zhangsan"
192.168.109.149:6380>
[root@bogon src]# ./redis-cli -p 6383 -c
127.0.0.1:6383> get name
-> Redirected to slot [5798] located at 192.168.109.149:6380
"zhangsan"
192.168.109.149:6380>
[root@bogon src]# ./redis-cli -p 6383 -c
127.0.0.1:6383> readonly
OK
127.0.0.1:6383> get name
"zhangsan"
127.0.0.1:6383>
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