Redis——Redis 集群cluster

￡神魔★判官ぃ 2023-01-13 14:59 210阅读 0赞

### Redis 集群cluster ###

*  集群简介
 *   *  集群作用
 *  Redis集群结构设计
 *   *  数据存储设计
     *  集群内部通讯设计
 *  cluster集群结构搭建
 *   *  主从下线和主从切换

# 集群简介 #

*  集群就是使用网络将若干台计算机联通起来，并提供统一的管理方式，使其对外呈现单机的服务效果

## 集群作用 ##

*  分散单台服务器的访问压力，实现负载均衡
 *  分散单台服务器的存储压力，实现可扩展性
 *  降低单台服务器宕机带来的业务灾难

# Redis集群结构设计 #

## 数据存储设计 ##

*  通过算法设计，计算出key应该保存的位置
 *  将所有的存储空间计划切割成16384份，每台主机保存一部分每份代表的是一个存储空间，不是一个key的保存空间
 *  将key按照计算出的结果放到对应的存储空间

1.  key通过hash算法计算出一个值，然后拿这个值%16384
2.  得到一个数（假如是37）为key的保存位置，然后再存入相应的存储空间位置  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NhbnRldmVubA_size_16_color_FFFFFF_t_70]
3.  假如又增加了一个节点，之前每个节点都会拿出部分槽给新的节点  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NhbnRldmVubA_size_16_color_FFFFFF_t_70 1]
4.  如果是去除节点，则把被去除节点的槽加入到存在的节点当作

## 集群内部通讯设计 ##

*  各个数据库互相通信，保存各个库中槽的编号数据

1.  客户端发出一个key访问A，通过算法计算出key的存储位置
2.  如果一次命中，直接返回
3.  一次未命中，告知具体位置
4.  一次命中或者两次命中提高数据访问效率  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0NhbnRldmVubA_size_16_color_FFFFFF_t_70 2]

# cluster集群结构搭建 #

*  原生安装（单条命令）
    
     *  配置服务器（3主3从）
     *  建立通信（Meet）
     *  分槽（Slot）
     *  搭建主从（master-slave）
 *  工具安装（批处理）

**Cluster配置**

*  添加节点
    
    > cluster-enabled yes|no
 *  cluster配置文件名，该文件属于自动生成，仅用于快速查找文件并查询文件内容
    
    > cluster-config-file
 *  节点服务响应超时时间，用于判定该节点是否下线或切换为从节点
    
    > cluster-node-timeout
 *  master连接的slave最小数量
    
    > cluster-migration-barrier

**Cluster节点操作命令**

*  查看集群节点信息
    
        cluster nodes
 *  进入一个从节点 redis，切换其主节点
    
        cluster replicate <master-id>
 *  发现一个新节点，新增主节点
    
        cluster meet ip:port
 *  忽略一个没有solt的节点
    
        cluster forget <id>
 *  手动故障转移
    
        cluster failover

首先清空之前的数据
    [root@maomao ~]# cd /usr/local/redis/data/
    [root@maomao data]# ls
    appendonly-6379.aof  dump-6379.rdb  dump.rdb
    [root@maomao data]# rm -rf * 
    
    配置文件添加
    cluster-enabled yes		# 开启cluster
    cluster-config-file nodes-6379.conf		# 配置文件和名字
    cluster-node-timeout 10000		# cluster下线时间，超时时间为10秒
    
    
    复制六个配置文件
    sed 's/6379/6380/g' redis-6379.conf > redis-6380.conf
    sed 's/6379/6381/g' redis-6379.conf > redis-6381.conf
    sed 's/6379/6382/g' redis-6379.conf > redis-6382.conf
    sed 's/6379/6383/g' redis-6379.conf > redis-6383.conf
    sed 's/6379/6384/g' redis-6379.conf > redis-6384.conf
    sed 's/6379/6385/g' redis-6379.conf > redis-6385.conf
    
    检查
    cat redis-6385.conf |grep -v '#' |grep -v '^$'
    
    开启服务
    redis-server redis_config/redis-6379.conf
    ...
    redis-server redis_config/redis-6384.conf
    
    [root@maomao bin]# ps aux |grep redis-
    root       2116  0.2  0.5 165020 10824 pts/0    Sl+  02:23   0:00 redis-server 127.0.0.1:6379 [cluster]
    root       2121  0.2  0.5 165020 10664 pts/7    Sl+  02:23   0:00 redis-server 127.0.0.1:6380 [cluster]
    root       2126  0.2  0.5 165020 10720 pts/6    Sl+  02:23   0:00 redis-server 127.0.0.1:6381 [cluster]
    root       2131  0.2  0.6 171164 12768 pts/2    Sl+  02:23   0:00 redis-server 127.0.0.1:6382 [cluster]
    root       2136  0.2  0.5 165020 10760 pts/5    Sl+  02:24   0:00 redis-server 127.0.0.1:6383 [cluster]
    root       2141  0.1  0.5 165020 10788 pts/1    Sl+  02:24   0:00 redis-server 127.0.0.1:6384 [cluster]
    
    redis-cli --cluster create 127.0.0.1:6379 127.0.0.1:6380 127.0.0.1:6381 127.0.0.1:6382 127.0.0.1:6383 127.0.0.1:6384 --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 127.0.0.1:6383 to 127.0.0.1:6379
    Adding replica 127.0.0.1:6384 to 127.0.0.1:6380
    Adding replica 127.0.0.1:6382 to 127.0.0.1:6381
    >>> Trying to optimize slaves allocation for anti-affinity
    [WARNING] Some slaves are in the same host as their master
    M: 56aa54f614a2fc8f99e30a109d5e6a91d723193e 127.0.0.1:6379
       slots:[0-5460] (5461 slots) master
    M: 083eb7940fb5d5444563e3a48d36a1609b8d5af4 127.0.0.1:6380
       slots:[5461-10922] (5462 slots) master
    M: f515c69256533ebb17d2aabefe81d6e630f7eee5 127.0.0.1:6381
       slots:[10923-16383] (5461 slots) master
    S: d25e2d50c3b6136cafc3cdd0a5fef0e86fbf66fb 127.0.0.1:6382
       replicates 56aa54f614a2fc8f99e30a109d5e6a91d723193e
    S: 86f0f88285ca648df41e8f348e41cf5ef520bdae 127.0.0.1:6383
       replicates 083eb7940fb5d5444563e3a48d36a1609b8d5af4
    S: 738d205c923600d6f7c8ea8df8313527b8267b95 127.0.0.1:6384
       replicates f515c69256533ebb17d2aabefe81d6e630f7eee5
    Can I set the above configuration? (type 'yes' to accept): 
    
    6379 6380 6381 是master
    6382 6383 6384 是slave
    slots 就是槽 三个master分的槽都一样多 平均分配
    
    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 127.0.0.1:6379)
    M: 56aa54f614a2fc8f99e30a109d5e6a91d723193e 127.0.0.1:6379
       slots:[0-5460] (5461 slots) master
       1 additional replica(s)
    S: d25e2d50c3b6136cafc3cdd0a5fef0e86fbf66fb 127.0.0.1:6382
       slots: (0 slots) slave
       replicates 56aa54f614a2fc8f99e30a109d5e6a91d723193e
    S: 86f0f88285ca648df41e8f348e41cf5ef520bdae 127.0.0.1:6383
       slots: (0 slots) slave
       replicates 083eb7940fb5d5444563e3a48d36a1609b8d5af4
    M: 083eb7940fb5d5444563e3a48d36a1609b8d5af4 127.0.0.1:6380
       slots:[5461-10922] (5462 slots) master
       1 additional replica(s)
    M: f515c69256533ebb17d2aabefe81d6e630f7eee5 127.0.0.1:6381
       slots:[10923-16383] (5461 slots) master
       1 additional replica(s)
    S: 738d205c923600d6f7c8ea8df8313527b8267b95 127.0.0.1:6384
       slots: (0 slots) slave
       replicates f515c69256533ebb17d2aabefe81d6e630f7eee5
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.
    
    可以查看日志
    [root@maomao bin]# cat /usr/local/redis/data/nodes-6379.conf 
    
    集群搭建完成
    测试
    [root@maomao bin]# redis-cli
    127.0.0.1:6379> set name maomao
    (error) MOVED 5798 127.0.0.1:6380	# 叫我们去这个槽操作
    
    [root@maomao bin]# redis-cli -c		# 操控集群使用 redis-cli -c
    127.0.0.1:6379> set name maomao
    -> Redirected to slot [5798] located at 127.0.0.1:6380
    OK
    
    我们在6382获取key 失败
    [root@maomao bin]# redis -cli -c -p 6382
    -bash: redis: command not found
    [root@maomao bin]# redis-cli -c -p 6382
    127.0.0.1:6382> get name
    -> Redirected to slot [5798] located at 
    127.0.0.1:6380
    "maomao"
    127.0.0.1:6380> exit
    
    连接到6380就能够获取key
    [root@maomao bin]# redis-cli -c -p 6380
    127.0.0.1:6380> get name
    "maomao"

## 主从下线和主从切换 ##

我们将一个主节点下线，然后查看信息
    
    127.0.0.1:6380> cluster nodes
    86f0f88285ca648df41e8f348e41cf5ef520bdae 127.0.0.1:6383@16383 slave 083eb7940fb5d5444563e3a48d36a1609b8d5af4 0 1618815771240 
    2 connected
    083eb7940fb5d5444563e3a48d36a1609b8d5af4 127.0.0.1:6380@16380 myself,master - 0 1618815770000 2 connected 5461-10922
    56aa54f614a2fc8f99e30a109d5e6a91d723193e 127.0.0.1:6379@16379 master,fail - 1618815743184 1618815740000 1 disconnected
    d25e2d50c3b6136cafc3cdd0a5fef0e86fbf66fb 127.0.0.1:6382@16382 master - 0 1618815768232 7 connected 0-5460
    f515c69256533ebb17d2aabefe81d6e630f7eee5 127.0.0.1:6381@16381 master - 0 1618815770000 3 connected 10923-16383
    738d205c923600d6f7c8ea8df8313527b8267b95 127.0.0.1:6384@16384 slave f515c69256533ebb17d2aabefe81d6e630f7eee5 0 1618815770238 
    3 connected
    
    master,fail意思是master会回来

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