Linux中使用redis（四）Redis集群（cluster模式）

朴灿烈づ我的快乐病毒、 2024-03-22 09:59 15阅读 0赞

## Redis集群（cluster模式） ##

### 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 ###

1.  容量不够，redis如何进行扩容？
2.  并发写操作， redis如何分摊？
3.  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。
4.  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、创建节点 ####

**1) 通过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.**

创建完后在Linux的/etc/redis路径下

[root@localhost utils]# ./install_server.sh 6379/6380/6381/.

![a8e028809df94d33a595dae780c4273c.png][]

#### 2、修改以下六个配置文件，**修改6个redis节点的配置文件** ####

![681551e4850540f9aa8b37af316ab699.png][]

port:63XX   # 设置成对应服务专属的端口号
    bind 0.0.0.0
    cluster-enabled yes
    cluster-config-file  nodes-63XX.conf # 设置成对应服务专属的名字
    cluster-node-timeout 15000
    daemonize yes
    protedted-mode no
    pidfile  /var/run/redis_63XX.pid
    dbfilename "dump6380.rdb"  # 设置成对应服务专属的名字

**1）如果各个节点原本有存储数据，则先将各个节**

[root@localhost src]# ps -ef | grep redis

**点的数据文件清空**

\-数据清空 flushdb命令清除**所有节点中（我的是6个节点，3主3从）**的数据

从机不能清空（从机只能读数据），只需要清空主机数据（3个主机）

![5fde4964272e424fa030808945da707a.png][]

#### 3、启动以上几个redis实例，**启动六个节点** ####

[root@localhost src]# ./redis-server /etc/redis/63XX.conf
    [root@localhost src]# ./redis-server /etc/redis/63XX.conf
    [root@localhost src]# ./redis-server /etc/redis/63XX.conf
    [root@localhost src]# ./redis-server /etc/redis/63XX.conf
    [root@localhost src]# ./redis-server /etc/redis/63XX.conf
    [root@localhost src]# ./redis-server /etc/redis/63XX.conf

#### 4、查看状态，**查看各个节点是否启动成功** ####

[root@localhost src]# ps -ef | grep redis

![1c9a5263f2ce421f8ee2ce2e75fd5eb8.png][]

#### 5、**配置集群**，配置静态IP （否则ip改变后集群失效）前三个是主节点，后三个是从节点 ####

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 192.168.100.128:6379 192.168.100.128:6383 192.168.100.128:6385 192.168.100.128:6387 192.168.100.128:6384 192.168.100.128:6386 --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 192.168.100.128:6384 to 192.168.100.128:6379
    Adding replica 192.168.100.128:6386 to 192.168.100.128:6383
    Adding replica 192.168.100.128:6387 to 192.168.100.128:6385
    >>> Trying to optimize slaves allocation for anti-affinity
    [WARNING] Some slaves are in the same host as their master
    M: caba0d507ac4b7c81be5323b5e151d3919b26ac6 192.168.100.128:6379
       slots:[0-5460] (5461 slots) master
    M: ef94cab7f5515a19a376f623dd4df2e98fbf165e 192.168.100.128:6383
       slots:[5461-10922] (5462 slots) master
    M: 0f2887a983843cbbae0cc6801b935f4847f58c76 192.168.100.128:6385
       slots:[10923-16383] (5461 slots) master
    S: 4dbea80400032284de9d161589e995e84a9271c5 192.168.100.128:6387
       replicates caba0d507ac4b7c81be5323b5e151d3919b26ac6
    S: 5081d02398c650c0565e77682396528f128cbca5 192.168.100.128:6384
       replicates ef94cab7f5515a19a376f623dd4df2e98fbf165e
    S: 40e7769f0c20dce718fa137b958c971996b36860 192.168.100.128:6386
       replicates 0f2887a983843cbbae0cc6801b935f4847f58c76
    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 192.168.100.128:6379)
    M: caba0d507ac4b7c81be5323b5e151d3919b26ac6 192.168.100.128:6379
       slots:[0-5460] (5461 slots) master
       1 additional replica(s)
    S: 5081d02398c650c0565e77682396528f128cbca5 192.168.100.128:6384
       slots: (0 slots) slave
       replicates ef94cab7f5515a19a376f623dd4df2e98fbf165e
    S: 40e7769f0c20dce718fa137b958c971996b36860 192.168.100.128:6386
       slots: (0 slots) slave
       replicates 0f2887a983843cbbae0cc6801b935f4847f58c76
    S: 4dbea80400032284de9d161589e995e84a9271c5 192.168.100.128:6387
       slots: (0 slots) slave
       replicates caba0d507ac4b7c81be5323b5e151d3919b26ac6
    M: 0f2887a983843cbbae0cc6801b935f4847f58c76 192.168.100.128:6385
       slots:[10923-16383] (5461 slots) master
       1 additional replica(s)
    M: ef94cab7f5515a19a376f623dd4df2e98fbf165e 192.168.100.128:6383
       slots:[5461-10922] (5462 slots) master
       1 additional replica(s)
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.

#### 6）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 192.168.100.128:6379
    192.168.100.128:6379 (caba0d50...) -> 1 keys | 5461 slots | 1 slaves.
    192.168.100.128:6385 (0f2887a9...) -> 0 keys | 5461 slots | 1 slaves.
    192.168.100.128:6383 (ef94cab7...) -> 1 keys | 5462 slots | 1 slaves.
    [OK] 2 keys in 3 masters.
    0.00 keys per slot on average.
    >>> Performing Cluster Check (using node 192.168.100.128:6379)
    M: caba0d507ac4b7c81be5323b5e151d3919b26ac6 192.168.100.128:6379
       slots:[0-5460] (5461 slots) master
       1 additional replica(s)
    S: 5081d02398c650c0565e77682396528f128cbca5 192.168.100.128:6384
       slots: (0 slots) slave
       replicates ef94cab7f5515a19a376f623dd4df2e98fbf165e
    S: 40e7769f0c20dce718fa137b958c971996b36860 192.168.100.128:6386
       slots: (0 slots) slave
       replicates 0f2887a983843cbbae0cc6801b935f4847f58c76
    S: 4dbea80400032284de9d161589e995e84a9271c5 192.168.100.128:6387
       slots: (0 slots) slave
       replicates caba0d507ac4b7c81be5323b5e151d3919b26ac6
    M: 0f2887a983843cbbae0cc6801b935f4847f58c76 192.168.100.128:6385
       slots:[10923-16383] (5461 slots) master
       1 additional replica(s)
    M: ef94cab7f5515a19a376f623dd4df2e98fbf165e 192.168.100.128:6383
       slots:[5461-10922] (5462 slots) master
       1 additional replica(s)
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.

#### 7、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>

#### 8、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

**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**

[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>

**根据图1主节点set的哈希值，通过哈希值找到图2对应的哈希值范围，找到对应的主节点**

![2d0845c2aca54abbb9c72c90455ad911.png][]

![c9a24f64a9be48348730c01583a08ef7.png][]

#### 9、报错信息 ####

启动集群会出现的报错信息：无法连接

![5802e0d8b75f412e9d7cce2c3d78dfbb.png][]

解决办法：

127.0.0.1:6385> shutdown
    [root@localhost src]# systemctl stop redis_6385.service
    [root@localhost src]# systemctl start redis_6385.service
    再次执行启动集群

[a8e028809df94d33a595dae780c4273c.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/77f1aeee109243b6902db5a51f8afc89.png
[681551e4850540f9aa8b37af316ab699.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/feb4bd7f5bb6456fb4324b73ec7e28ac.png
[5fde4964272e424fa030808945da707a.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/838278746a7744e2b498fce35bc071ca.png
[1c9a5263f2ce421f8ee2ce2e75fd5eb8.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/3f3de8c64001463aa35186c62782538d.png
[2d0845c2aca54abbb9c72c90455ad911.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/c7882d7a394348e0aeb9fe9c8a55fd72.png
[c9a24f64a9be48348730c01583a08ef7.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/65af8b9e8bdc4a02985ac852608996f8.png
[5802e0d8b75f412e9d7cce2c3d78dfbb.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/22/58d6bda0795c40c58acbdca5a41e7afb.png