redis入门——集群篇

迈不过友情╰ 2022-07-12 05:26 186阅读 0赞

# redis入门——集群篇 #

@(Redis)\[服务器, 集群, 主从复制, jedis\]

*  redis入门集群篇
    
     *  主从复制
        
         *  基本介绍
         *  主从配置
            
             *  主redis配置
             *  从redis配置
     *  Redis集群
        
         *  基本介绍
         *  集群原理
            
             *  redis-cluster架构图
             *  redis-cluster投票容错
         *  Redis集群搭建
            
             *  Ruby环境
             *  redis配置文件修改
             *  编写集群启动脚本和停止脚本
                
                 *  启动脚本start-allsh
                 *  停止脚本stop-allsh
                 *  修改权限
             *  启动节点
             *  执行创建集群命令
                
                 *  成功启动信息
                 *  异常
         *  Redis集群节点的操作
            
             *  查询集群信息
             *  添加主节点
                
                 *  hash槽重新分配
             *  添加从节点
             *  删除结点
         *  客户端对Redis集群的使用方法
            
             *  使用redis命令行客户端连接
             *  使用jedis连接

## 主从复制 ##

### 基本介绍 ###

Redis 支持简单且易用的主从复制`master-slave replication`功能， 该功能可以让从服务器`slave server`成为主服务器`master server`的精确复制品。

以下是关于 `Redis` 复制功能的几个重要方面：

*  `Redis` 使用异步复制。 从 `Redis 2.8` 开始， 从服务器会以每秒一次的频率向主服务器报告复制流`replication stream`的处理进度。
 *  一个主服务器可以有多个从服务器。
 *  不仅主服务器可以有从服务器， 从服务器也可以有自己的从服务器， 多个从服务器之间可以构成一个图状结构。
 *  复制功能不会阻塞主服务器： 即使有一个或多个从服务器正在进行初次同步， 主服务器也可以继续处理命令请求。
 *  复制功能也不会阻塞从服务器： 只要在 `redis.conf` 文件中进行了相应的设置， 即使从服务器正在进行初次同步， 服务器也可以使用旧版本的数据集来处理命令查询。
    
    不过， 在从服务器删除旧版本数据集并载入新版本数据集的那段时间内， 连接请求会被阻塞。
    
    你还可以配置从服务器， 让它在与主服务器之间的连接断开时， 向客户端发送一个错误。
 *  复制功能可以单纯地用于数据冗余`data redundancy`， 也可以通过让多个从服务器处理只读命令请求来提升扩展性`scalability`： 比如说， 繁重的 `SORT` 命令可以交给附属节点去运行。
 *  可以通过复制功能来让主服务器免于执行持久化操作： 只要关闭主服务器的持久化功能， 然后由从服务器去执行持久化操作即可。

### 主从配置 ###

#### 主redis配置 ####

无需特殊配置。

#### 从redis配置 ####

修改从`redis`服务器上的`redis.conf`文件添加`slaveof <masterip> <masterport>`

# Master-Slave replication. Use slaveof to make a Redis instance a copy of
    # another Redis server. A few things to understand ASAP about Redis replication.
    #
    # 1) Redis replication is asynchronous, but you can configure a master to
    #    stop accepting writes if it appears to be not connected with at least
    #    a given number of slaves.
    # 2) Redis slaves are able to perform a partial resynchronization with the
    #    master if the replication link is lost for a relatively small amount of
    #    time. You may want to configure the replication backlog size (see the next
    #    sections of this file) with a sensible value depending on your needs.
    # 3) Replication is automatic and does not need user intervention. After a
    #    network partition slaves automatically try to reconnect to masters
    #    and resynchronize with them.
    #
    slaveof 192.168.37.131 6379

上边的配置说明当前该从`redis`服务器所对应的主`redis`是`192.168.37.131`，端口是`6379`

## Redis集群 ##

### 基本介绍 ###

`Redis` 集群是一个可以在多个 `Redis` 节点之间进行数据共享的设施`installation`。

`Redis` 集群不支持那些需要同时处理多个键的 `Redis` 命令， 因为执行这些命令需要在多个 `Redis` 节点之间移动数据， 并且在高负载的情况下， 这些命令将降低`Redis`集群的性能， 并导致不可预测的行为。

`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。

`Redis`集群提供了以下两个好处：

*  将数据自动切分`split`到多个节点的能力。
 *  当集群中的一部分节点失效或者无法进行通讯时， 仍然可以继续处理命令请求的能力。

### 集群原理 ###

#### redis-cluster架构图 ####

![redis-cluster架构图][redis-cluster]

1.  所有的`redis`节点彼此互联(`PING`\-`PONG`机制),内部使用二进制协议优化传输速度和带宽。
2.  节点的`fail`是通过集群中超过半数的节点检测失效时才生效。
3.  客户端与`redis`节点直连,不需要中间`proxy`层.客户端不需要连接集群所有节点,连接集群中任何一个可用节点即可。
4.  `redis-cluster`把所有的物理节点映射到\[`0-16383`\]`slot`上,`cluster` 负责维护`node`<->`slot`<->`value`

`Redis`集群中内置了 `16384` 个哈希槽，当需要在 `Redis` 集群中放置一个 `key-value` 时，`redis` 先对 `key` 使用 `crc16` 算法算出一个结果，然后把结果对 `16384` 求余数，这样每个 `key` 都会对应一个编号在 `0-16383` 之间的哈希槽，`redis` 会根据节点数量大致均等的将哈希槽映射到不同的节点

#### redis-cluster投票:容错 ####

![redis-cluster投票:容错][redis-cluster 1]

1.  投票过程是集群中所有`master`参与,如果半数以上`master`节点与`master`节点通信超时(`cluster-node-timeout`),认为当前`master`节点挂掉.
2.  什么时候整个集群不可用(`cluster_state:fail`)?
    
     *  如果集群任意`master`挂掉,且当前`master`没有`slave`.集群进入`fail`状态,也可以理解成集群的`slot`映射\[`0-16383`\]不完整时进入fail状态.  
        
        
         *  `redis-3.0.0.rc1`加入`cluster-require-full-coverage`参数,默认关闭,打开集群兼容部分失败.
     *  如果集群超过半数以上`master`挂掉，无论是否有`slave`，集群进入`fail`状态.

### Redis集群搭建 ###

`Redis`单机版的安装见博客《redis入门——安装篇》，安装好之后，将`redis`复制成`6`份，注意要将`.rdb`和`.aof`后缀的文件删除，如果有的话。

#### Ruby环境 ####

使用

yum -y install ruby
    yum -y install rubygems

安装ruby环境。  
网上下载`redis-3.0.0.gem`，执行`gem install redis-3.0.0.gem`安装。

#### redis配置文件修改 ####

现在已经准备好了，`6`份干净的`redis`，如下所示

[root@localhost redis-cluster]# pwd
    /usr/local/redis/redis-cluster
    [root@localhost redis-cluster]# ll
    total 72
    drwxr-xr-x 2 root root  4096 Nov  2 00:17 redis1
    drwxr-xr-x 2 root root  4096 Nov  2 00:25 redis2
    drwxr-xr-x 2 root root  4096 Nov  2 00:25 redis3
    drwxr-xr-x 2 root root  4096 Nov  2 00:25 redis4
    drwxr-xr-x 2 root root  4096 Nov  2 00:25 redis5
    drwxr-xr-x 2 root root  4096 Nov  2 00:25 redis6
    -rwxr-xr-x 1 root root 48141 Nov  2 00:16 redis-trib.rb
    [root@localhost redis-cluster]#

PS：注意，这里已经将`redis`源文件`src`目录下的`redis-trib.rb`文件拷贝过来了。  
`redis-trib.rb`这个文件是`redis`集群的管理文件，`ruby`脚本。

将六个节点的`redis.conf`配置文件按照如下进行修改

################################ GENERAL #####################################
    
    # By default Redis does not run as a daemon. Use 'yes' if you need it.
    # Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
    daemonize yes
    
    # Accept connections on the specified port, default is 6379.
    # If port 0 is specified Redis will not listen on a TCP socket.
    port *
    
    ################################ REDIS CLUSTER ###############################
    #
    # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    # WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however
    # in order to mark it as "mature" we need to wait for a non trivial percentage
    # of users to deploy it in production.
    # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    #
    # Normal Redis instances can't be part of a Redis Cluster; only nodes that are
    # started as cluster nodes can. In order to start a Redis instance as a
    # cluster node enable the cluster support uncommenting the following:
    #
    cluster-enabled yes

PS：端口号如果是同一台主机的话，必须不同。不同主机可以相同。

PS：我这里是使用一台主机，所以我将六个节点的端口号修改为`7001`\-`7006`

#### 编写集群启动脚本和停止脚本 ####

##### 启动脚本start-all.sh #####

cd redis1
    ./redis-server redis.conf
    cd ..
    cd redis2
    ./redis-server redis.conf
    cd ..
    cd redis3
    ./redis-server redis.conf
    cd ..
    cd redis4
    ./redis-server redis.conf
    cd ..
    cd redis5
    ./redis-server redis.conf
    cd ..
    cd redis6
    ./redis-server redis.conf
    cd ..

##### 停止脚本stop-all.sh #####

./redis1/redis-cli -p 7001 shutdown
    ./redis1/redis-cli -p 7002 shutdown
    ./redis1/redis-cli -p 7003 shutdown
    ./redis1/redis-cli -p 7004 shutdown
    ./redis1/redis-cli -p 7005 shutdown
    ./redis1/redis-cli -p 7006 shutdown

PS：两个脚本都放在如下所属目录

[root@localhost redis-cluster]# pwd
    /usr/local/redis/redis-cluster
    [root@localhost redis-cluster]# ll
    total 80
    drwxr-xr-x 2 root root  4096 Nov  2 00:52 redis1
    drwxr-xr-x 2 root root  4096 Nov  2 00:51 redis2
    drwxr-xr-x 2 root root  4096 Nov  2 00:53 redis3
    drwxr-xr-x 2 root root  4096 Nov  2 00:53 redis4
    drwxr-xr-x 2 root root  4096 Nov  2 00:53 redis5
    drwxr-xr-x 2 root root  4096 Nov  2 00:53 redis6
    -rwxr-xr-x 1 root root 48141 Nov  2 00:16 redis-trib.rb
    -rw-r--r-- 1 root root   252 Nov  2 00:55 start-all.sh
    -rw-r--r-- 1 root root   216 Nov  2 00:57 stop-all.sh
    [root@localhost redis-cluster]#

##### 修改权限 #####

[root@localhost redis-cluster]# chmod -u+x start-all.sh stop-all.sh

#### 启动节点 ####

[root@localhost redis-cluster]# ./start-all.sh 
    [root@localhost redis-cluster]# ps aux | grep redis
    root      2924  0.8  0.1  33932  2048 ?        Ssl  Nov01   3:53 ./redis-server *:6379 [cluster]
    root     11924  0.0  0.1  33936  1948 ?        Ssl  01:01   0:00 ./redis-server *:7001 [cluster]
    root     11928  0.0  0.1  33936  1952 ?        Ssl  01:01   0:00 ./redis-server *:7002 [cluster]
    root     11932  0.0  0.1  33936  1948 ?        Ssl  01:01   0:00 ./redis-server *:7003 [cluster]
    root     11936  0.0  0.1  33936  1952 ?        Ssl  01:01   0:00 ./redis-server *:7004 [cluster]
    root     11940  0.0  0.1  33936  1952 ?        Ssl  01:01   0:00 ./redis-server *:7005 [cluster]
    root     11944  0.0  0.1  33936  1948 ?        Ssl  01:01   0:00 ./redis-server *:7006 [cluster]
    root     11948  0.0  0.0   4360   748 pts/2    S+   01:01   0:00 grep redis
    [root@localhost redis-cluster]#

#### 执行创建集群命令 ####

[root@localhost redis-cluster]# pwd
    /usr/local/redis/redis-cluster
    [root@localhost redis-cluster]# ./redis-trib.rb create --replicas 1 192.168.37.131:7001 192.168.37.131:7002 192.168.37.131:7003 192.168.37.131:7004 192.168.37.131:7005  192.168.37.131:7006

##### 成功启动信息 #####

>>> Creating cluster
    Connecting to node 192.168.37.131:7001: OK
    Connecting to node 192.168.37.131:7002: OK
    Connecting to node 192.168.37.131:7003: OK
    Connecting to node 192.168.37.131:7004: OK
    Connecting to node 192.168.37.131:7005: OK
    Connecting to node 192.168.37.131:7006: OK
    >>> Performing hash slots allocation on 6 nodes...
    Using 3 masters:
    192.168.37.131:7001
    192.168.37.131:7002
    192.168.37.131:7003
    Adding replica 192.168.37.131:7004 to 192.168.37.131:7001
    Adding replica 192.168.37.131:7005 to 192.168.37.131:7002
    Adding replica 192.168.37.131:7006 to 192.168.37.131:7003
    M: 8b153503b52f83634e04b0077f32ef629ad91ee6 192.168.37.131:7001
       slots:0-5460 (5461 slots) master
    M: f89799066dd8ecaaa1430559be4ce9c8c87055d8 192.168.37.131:7002
       slots:5461-10922 (5462 slots) master
    M: 53d698ad56b09f89cfef34850213e2d0a44154dd 192.168.37.131:7003
       slots:10923-16383 (5461 slots) master
    S: e73204399d08c14def1f71d0c5377cbc757dc4b8 192.168.37.131:7004
       replicates 8b153503b52f83634e04b0077f32ef629ad91ee6
    S: 1d5dcc8d1ccb6bce55efc3e3aadc690dc77808d8 192.168.37.131:7005
       replicates f89799066dd8ecaaa1430559be4ce9c8c87055d8
    S: e9458233cb85bd897ff694003e6d8a834eba2b44 192.168.37.131:7006
       replicates 53d698ad56b09f89cfef34850213e2d0a44154dd
    Can I set the above configuration? (type 'yes' to accept): y
    *** Aborting...
    [root@localhost redis-cluster]# ./redis-trib.rb create --replicas 1 192.168.37.131:7001 192.168.37.131:7002 192.168.37.131:7003 192.168.37.131:7004 192.168.37.131:7005  192.168.37.131:7006
    >>> Creating cluster
    Connecting to node 192.168.37.131:7001: OK
    Connecting to node 192.168.37.131:7002: OK
    Connecting to node 192.168.37.131:7003: OK
    Connecting to node 192.168.37.131:7004: OK
    Connecting to node 192.168.37.131:7005: OK
    Connecting to node 192.168.37.131:7006: OK
    >>> Performing hash slots allocation on 6 nodes...
    Using 3 masters:
    192.168.37.131:7001
    192.168.37.131:7002
    192.168.37.131:7003
    Adding replica 192.168.37.131:7004 to 192.168.37.131:7001
    Adding replica 192.168.37.131:7005 to 192.168.37.131:7002
    Adding replica 192.168.37.131:7006 to 192.168.37.131:7003
    M: 8b153503b52f83634e04b0077f32ef629ad91ee6 192.168.37.131:7001
       slots:0-5460 (5461 slots) master
    M: f89799066dd8ecaaa1430559be4ce9c8c87055d8 192.168.37.131:7002
       slots:5461-10922 (5462 slots) master
    M: 53d698ad56b09f89cfef34850213e2d0a44154dd 192.168.37.131:7003
       slots:10923-16383 (5461 slots) master
    S: e73204399d08c14def1f71d0c5377cbc757dc4b8 192.168.37.131:7004
       replicates 8b153503b52f83634e04b0077f32ef629ad91ee6
    S: 1d5dcc8d1ccb6bce55efc3e3aadc690dc77808d8 192.168.37.131:7005
       replicates f89799066dd8ecaaa1430559be4ce9c8c87055d8
    S: e9458233cb85bd897ff694003e6d8a834eba2b44 192.168.37.131:7006
       replicates 53d698ad56b09f89cfef34850213e2d0a44154dd
    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 192.168.37.131:7001)
    M: 8b153503b52f83634e04b0077f32ef629ad91ee6 192.168.37.131:7001
       slots:0-5460 (5461 slots) master
    M: f89799066dd8ecaaa1430559be4ce9c8c87055d8 192.168.37.131:7002
       slots:5461-10922 (5462 slots) master
    M: 53d698ad56b09f89cfef34850213e2d0a44154dd 192.168.37.131:7003
       slots:10923-16383 (5461 slots) master
    M: e73204399d08c14def1f71d0c5377cbc757dc4b8 192.168.37.131:7004
       slots: (0 slots) master
       replicates 8b153503b52f83634e04b0077f32ef629ad91ee6
    M: 1d5dcc8d1ccb6bce55efc3e3aadc690dc77808d8 192.168.37.131:7005
       slots: (0 slots) master
       replicates f89799066dd8ecaaa1430559be4ce9c8c87055d8
    M: e9458233cb85bd897ff694003e6d8a834eba2b44 192.168.37.131:7006
       slots: (0 slots) master
       replicates 53d698ad56b09f89cfef34850213e2d0a44154dd
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.
    [root@localhost redis-cluster]#

##### 异常 #####

>>> Creating cluster
    Connecting to node 192.168.37.131:7001: OK
    [ERR] Node 192.168.37.131:7001 is not empty. Either the node already knows other nodes (check with CLUSTER NODES) or contains some key in database 0.

解决方法是删除生成的配置文件`nodes.conf`，如果不行则说明现在创建的结点包括了旧集群的结点信息，需要删除`redis`的持久化文件后再重启`redis`，比如：`appendonly.aof`、`dump.rdb`

首先，使用`stop-all.sh`停止服务

[root@localhost redis-cluster]# ./stop-all.sh
    [root@localhost redis-cluster]# ps aux | grep redis
    root      2924  0.8  0.1  33932  2048 ?        Ssl  Nov01   3:54 ./redis-server *:6379 [cluster]
    root     11969  0.0  0.0   4360   744 pts/2    S+   01:10   0:00 grep redis
    [root@localhost redis-cluster]#

然后每个节点中的`appendonly.aof`、`dump.rdb` 、`nodes.conf`。

[root@localhost redis-cluster]# rm -f redis*/dump.rdb
    [root@localhost redis-cluster]# rm -f redis*/appendonly.aof
    [root@localhost redis-cluster]# rm -f redis*/nodes.conf

然后使用脚本`start-all.sh`启动，再启动集群管理服务。

[root@localhost redis-cluster]# ./start-all.sh 
    [root@localhost redis-cluster]# ps aux | grep redis
    root      2924  0.8  0.1  33932  2048 ?        Ssl  Nov01   3:54 ./redis-server *:6379 [cluster]
    root     11980  0.0  0.1  33936  1952 ?        Ssl  01:12   0:00 ./redis-server *:7001 [cluster]
    root     11982  0.0  0.1  33936  1952 ?        Ssl  01:12   0:00 ./redis-server *:7002 [cluster]
    root     11984  0.0  0.1  33936  1952 ?        Ssl  01:12   0:00 ./redis-server *:7003 [cluster]
    root     11986  0.0  0.1  33936  1952 ?        Ssl  01:12   0:00 ./redis-server *:7004 [cluster]
    root     11988  0.0  0.1  33936  1948 ?        Ssl  01:12   0:00 ./redis-server *:7005 [cluster]
    root     11990  0.0  0.1  33936  1948 ?        Ssl  01:12   0:00 ./redis-server *:7006 [cluster]
    root     12004  0.0  0.0   4360   748 pts/2    S+   01:12   0:00 grep redis
    [root@localhost redis-cluster]# ./redis-trib.rb create --replicas 1 192.168.37.131:7001 192.168.37.131:7002 192.168.37.131:7003 192.168.37.131:7004 192.168.37.131:7005  192.168.37.131:7006
    [root@localhost redis-cluster]#

### Redis集群节点的操作 ###

#### 查询集群信息 ####

集群创建成功登陆任意`redis`结点查询集群中的节点情况。

客户端以集群方式登陆：

[root@localhost redis-cluster]# ./redis1/redis-cli -c -h 192.168.37.131 -p 7001
    192.168.37.131:7001>

说明：  
`./redis1/redis-cli -c -h 192.168.37.131 -p 7001` ，其中`-c`表示以集群方式连接`redis`，`-h`指定`ip`地址，`-p`指定端口号

`cluster nodes` 查询集群结点信息

192.168.37.131:7001> cluster nodes
    8e1186475f87c928e8a146d3804d9a2697246ad0 192.168.37.131:7003 master - 0 1478085160899 3 connected 10923-16383
    80de7003738f74134a3403fc939fed253b7774f2 192.168.37.131:7004 master - 0 1478085156858 8 connected 0-5460
    652caf5daf7971135679951324eba7b50e99251a 192.168.37.131:7005 slave 3adba62fdcc331ce231ca580cd2c8701e047bc6d 0 1478085158876 9 connected
    1cd6482fd7038d78ad556b52b0cb9e2590ad5598 192.168.37.131:7001 myself,slave 80de7003738f74134a3403fc939fed253b7774f2 0 0 1 connected
    3adba62fdcc331ce231ca580cd2c8701e047bc6d 192.168.37.131:7002 master - 0 1478085159889 9 connected 5461-10922
    cf23ca6d78cba3d3924065e1f7a394f6c51d4b28 192.168.37.131:7006 slave 8e1186475f87c928e8a146d3804d9a2697246ad0 0 1478085157867 6 connected
    192.168.37.131:7001>

`cluster info` 查询集群状态信息

192.168.37.131:7001> cluster info
    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:9
    cluster_my_epoch:8
    cluster_stats_messages_sent:12727
    cluster_stats_messages_received:10820
    192.168.37.131:7001>

#### 添加主节点 ####

集群创建成功后可以向集群中添加节点，下面是添加一个`master`主节点。

首先，准备一个干净的`redis`节点。按上面集群版修改`redis`配置文件。开启该`redis`节点。

查看`redis`进程

[root@localhost redis-cluster]# !ps
    ps aux | grep redis
    root      2924  0.6  0.1  33932  1800 ?        Ssl  Nov01   4:08 ./redis-server *:6379 [cluster]
    root     11980  0.0  0.2  33936  2216 ?        Ssl  01:12   0:09 ./redis-server *:7001 [cluster]
    root     11982  0.0  0.2  33936  2244 ?        Ssl  01:12   0:09 ./redis-server *:7002 [cluster]
    root     11984  0.0  0.2  33936  2220 ?        Ssl  01:12   0:09 ./redis-server *:7003 [cluster]
    root     11986  0.0  0.2  33936  2216 ?        Ssl  01:12   0:09 ./redis-server *:7004 [cluster]
    root     11988  0.0  0.2  33936  2228 ?        Ssl  01:12   0:09 ./redis-server *:7005 [cluster]
    root     11990  0.0  0.2  33936  2212 ?        Ssl  01:12   0:09 ./redis-server *:7006 [cluster]
    root     13913  0.0  0.1  33936  1952 ?        Ssl  04:21   0:00 ./redis7/redis-server *:7007 [cluster]   
    root     13917  0.0  0.0   4360   728 pts/3    S+   04:21   0:00 grep redis
    [root@localhost redis-cluster]#

执行下边命令：

[root@localhost redis-cluster]# ./redis-trib.rb add-node 192.168.37.131:7007 192.168.37.131:7001
    >>> Adding node 192.168.37.131:7007 to cluster 192.168.37.131:7001
    Connecting to node 192.168.37.131:7001: OK
    Connecting to node 192.168.37.131:7003: OK
    Connecting to node 192.168.37.131:7004: OK
    Connecting to node 192.168.37.131:7005: OK
    Connecting to node 192.168.37.131:7002: OK
    Connecting to node 192.168.37.131:7006: OK
    >>> Performing Cluster Check (using node 192.168.37.131:7001)
    S: 1cd6482fd7038d78ad556b52b0cb9e2590ad5598 192.168.37.131:7001
       slots: (0 slots) slave
       replicates 80de7003738f74134a3403fc939fed253b7774f2
    M: 8e1186475f87c928e8a146d3804d9a2697246ad0 192.168.37.131:7003
       slots:10923-16383 (5461 slots) master
       1 additional replica(s)
    M: 80de7003738f74134a3403fc939fed253b7774f2 192.168.37.131:7004
       slots:0-5460 (5461 slots) master
       1 additional replica(s)
    S: 652caf5daf7971135679951324eba7b50e99251a 192.168.37.131:7005
       slots: (0 slots) slave
       replicates 3adba62fdcc331ce231ca580cd2c8701e047bc6d
    M: 3adba62fdcc331ce231ca580cd2c8701e047bc6d 192.168.37.131:7002
       slots:5461-10922 (5462 slots) master
       1 additional replica(s)
    S: cf23ca6d78cba3d3924065e1f7a394f6c51d4b28 192.168.37.131:7006
       slots: (0 slots) slave
       replicates 8e1186475f87c928e8a146d3804d9a2697246ad0
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.
    Connecting to node 192.168.37.131:7007: OK
    >>> Send CLUSTER MEET to node 192.168.37.131:7007 to make it join the cluster.
    [OK] New node added correctly.
    [root@localhost redis-cluster]#

查看集群结点发现`7007`已添加到集群中：

[root@localhost redis-cluster]# ./redis1/redis-cli -c -h 192.168.37.131 -p 7001
    192.168.37.131:7001> cluster nodes
    8e1186475f87c928e8a146d3804d9a2697246ad0 192.168.37.131:7003 master - 0 1478085870038 3 connected 10923-16383
    80de7003738f74134a3403fc939fed253b7774f2 192.168.37.131:7004 master - 0 1478085868020 8 connected 0-5460
    652caf5daf7971135679951324eba7b50e99251a 192.168.37.131:7005 slave 3adba62fdcc331ce231ca580cd2c8701e047bc6d 0 1478085874075 9 connected
    1cd6482fd7038d78ad556b52b0cb9e2590ad5598 192.168.37.131:7001 myself,slave 80de7003738f74134a3403fc939fed253b7774f2 0 0 1 connected
    3adba62fdcc331ce231ca580cd2c8701e047bc6d 192.168.37.131:7002 master - 0 1478085873064 9 connected 5461-10922
    cf23ca6d78cba3d3924065e1f7a394f6c51d4b28 192.168.37.131:7006 slave 8e1186475f87c928e8a146d3804d9a2697246ad0 0 1478085875086 6 connected
    5d6c61ecff23bff3b0fb01a86c66d882f2d402a0 192.168.37.131:7007 master - 0 1478085872056 0 connected
    192.168.37.131:7001>

##### hash槽重新分配 #####

添加完主节点需要对主节点进行`hash`槽分配这样该主节才可以存储数据。  
`redis`集群有`16384`个槽，集群中的每个`master`结点分配一些槽，通过查看集群结点可以看到槽占用情况。

给刚添加的`7007`结点分配槽：

第一步：连接上集群  
`./redis-trib.rb reshard 192.168.37.131:7001`（连接集群中任意一个可用结点都行）

[root@localhost redis-cluster]# ./redis-trib.rb reshard 192.168.37.131:7001
    Connecting to node 192.168.37.131:7001: OK
    Connecting to node 192.168.37.131:7003: OK
    Connecting to node 192.168.37.131:7004: OK
    Connecting to node 192.168.37.131:7005: OK
    Connecting to node 192.168.37.131:7002: OK
    Connecting to node 192.168.37.131:7006: OK
    Connecting to node 192.168.37.131:7007: OK
    >>> Performing Cluster Check (using node 192.168.37.131:7001)
    S: 1cd6482fd7038d78ad556b52b0cb9e2590ad5598 192.168.37.131:7001
       slots: (0 slots) slave
       replicates 80de7003738f74134a3403fc939fed253b7774f2
    M: 8e1186475f87c928e8a146d3804d9a2697246ad0 192.168.37.131:7003
       slots:10923-16383 (5461 slots) master
       1 additional replica(s)
    M: 80de7003738f74134a3403fc939fed253b7774f2 192.168.37.131:7004
       slots:0-5460 (5461 slots) master
       1 additional replica(s)
    S: 652caf5daf7971135679951324eba7b50e99251a 192.168.37.131:7005
       slots: (0 slots) slave
       replicates 3adba62fdcc331ce231ca580cd2c8701e047bc6d
    M: 3adba62fdcc331ce231ca580cd2c8701e047bc6d 192.168.37.131:7002
       slots:5461-10922 (5462 slots) master
       1 additional replica(s)
    S: cf23ca6d78cba3d3924065e1f7a394f6c51d4b28 192.168.37.131:7006
       slots: (0 slots) slave
       replicates 8e1186475f87c928e8a146d3804d9a2697246ad0
    M: 5d6c61ecff23bff3b0fb01a86c66d882f2d402a0 192.168.37.131:7007
       slots: (0 slots) master
       0 additional replica(s)
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.
    How many slots do you want to move (from 1 to 16384)?

第二步：输入要分配的槽数量

How many slots do you want to move (from 1 to 16384)? 1000 What is the receiving node ID?

输入`1000`表示要分配`1000`个槽

第三步：输入接收槽的结点`id`

这里准备给`7007`分配槽，通过`cluster nodes`查看`7007`结点`id`为`5d6c61ecff23bff3b0fb01a86c66d882f2d402a0`

输入：`5d6c61ecff23bff3b0fb01a86c66d882f2d402a0`

What is the receiving node ID? 5d6c61ecff23bff3b0fb01a86c66d882f2d402a0
    Please enter all the source node IDs.
      Type 'all' to use all the nodes as source nodes for the hash slots.
      Type 'done' once you entered all the source nodes IDs.
    Source node #1:

第四步：输入源结点`id`  
输入源结点`id`，槽将从源结点中拿，分配后的槽在源结点中就不存在了。  
输入`all`表示从所有源结点中获取槽。  
输入`done`取消分配。

这里输入`all`

Source node #1:all
    
    省略了很多
    
        Moving slot 11253 from 8e1186475f87c928e8a146d3804d9a2697246ad0
        Moving slot 11254 from 8e1186475f87c928e8a146d3804d9a2697246ad0
        Moving slot 11255 from 8e1186475f87c928e8a146d3804d9a2697246ad0
    Do you want to proceed with the proposed reshard plan (yes/no)?

第五步：输入`yes`开始移动槽到目标结点`id`

省略了很多
    
    Moving slot 11253 from 192.168.37.131:7003 to 192.168.37.131:7007: 
    Moving slot 11254 from 192.168.37.131:7003 to 192.168.37.131:7007: 
    Moving slot 11255 from 192.168.37.131:7003 to 192.168.37.131:7007: 
    [root@localhost redis-cluster]#

第六步：查看结点信息

[root@localhost redis-cluster]# ./redis1/redis-cli -c -h 192.168.37.131 -p 7001
    192.168.37.131:7001> cluster nodes
    8e1186475f87c928e8a146d3804d9a2697246ad0 192.168.37.131:7003 master - 0 1478086754466 3 connected 11256-16383
    80de7003738f74134a3403fc939fed253b7774f2 192.168.37.131:7004 master - 0 1478086758509 8 connected 333-5460
    652caf5daf7971135679951324eba7b50e99251a 192.168.37.131:7005 slave 3adba62fdcc331ce231ca580cd2c8701e047bc6d 0 1478086756490 9 connected
    1cd6482fd7038d78ad556b52b0cb9e2590ad5598 192.168.37.131:7001 myself,slave 80de7003738f74134a3403fc939fed253b7774f2 0 0 1 connected
    3adba62fdcc331ce231ca580cd2c8701e047bc6d 192.168.37.131:7002 master - 0 1478086757500 9 connected 5795-10922
    cf23ca6d78cba3d3924065e1f7a394f6c51d4b28 192.168.37.131:7006 slave 8e1186475f87c928e8a146d3804d9a2697246ad0 0 1478086755477 6 connected
    5d6c61ecff23bff3b0fb01a86c66d882f2d402a0 192.168.37.131:7007 master - 0 1478086759518 10 connected 0-332 5461-5794 10923-11255
    192.168.37.131:7001>

查看结点信息，可以发现`7007`结点已经从三个主节点中获取了`slot`。

#### 添加从节点 ####

集群创建成功后可以向集群中添加节点，下面是添加一个`slave`从节点。  
添加`7008`从结点，将`7008`作为`7007`的从结点。

首先，准备一个干净的`redis`节点。按上面集群版修改`redis`配置文件。开启该`redis`节点。

查看`redis`进程

[root@localhost redis-cluster]# ps aux | grep redis
    root      2924  0.5  0.1  33932  1800 ?        Ssl  Nov01   4:12 ./redis-server *:6379 [cluster]
    root     11980  0.0  0.2  33936  2308 ?        Ssl  01:12   0:13 ./redis-server *:7001 [cluster]
    root     11982  0.0  0.2  33936  2288 ?        Ssl  01:12   0:13 ./redis-server *:7002 [cluster]
    root     11984  0.0  0.2  33936  2236 ?        Ssl  01:12   0:13 ./redis-server *:7003 [cluster]
    root     11986  0.0  0.2  33936  2288 ?        Ssl  01:12   0:13 ./redis-server *:7004 [cluster]
    root     11988  0.0  0.2  33936  2248 ?        Ssl  01:12   0:13 ./redis-server *:7005 [cluster]
    root     11990  0.0  0.2  33936  2244 ?        Ssl  01:12   0:13 ./redis-server *:7006 [cluster]
    root     13913  0.1  0.2  33936  2092 ?        Ssl  04:21   0:04 ./redis7/redis-server *:7007 [cluster]   
    root     14000  0.1  0.1  33936  1948 ?        Ssl  05:24   0:00 ./redis-server *:7008 [cluster]
    root     14006  0.0  0.0   4360   732 pts/3    S+   05:24   0:00 grep redis
    [root@localhost redis-cluster]#

命令格式为：

./redis-trib.rb add-node --slave --master-id 主节点id 添加节点的ip和端口 集群中已存在节点ip和端口

执行如下命令：

[root@localhost redis-cluster]# ./redis-trib.rb add-node --slave --master-id 5d6c61ecff23bff3b0fb01a86c66d882f2d402a0 192.168.37.131:7008 192.168.37.131:7001
    >>> Adding node 192.168.37.131:7008 to cluster 192.168.37.131:7001
    Connecting to node 192.168.37.131:7001: OK
    Connecting to node 192.168.37.131:7003: OK
    Connecting to node 192.168.37.131:7004: OK
    Connecting to node 192.168.37.131:7005: OK
    Connecting to node 192.168.37.131:7002: OK
    Connecting to node 192.168.37.131:7006: OK
    Connecting to node 192.168.37.131:7007: OK
    >>> Performing Cluster Check (using node 192.168.37.131:7001)
    S: 1cd6482fd7038d78ad556b52b0cb9e2590ad5598 192.168.37.131:7001
       slots: (0 slots) slave
       replicates 80de7003738f74134a3403fc939fed253b7774f2
    M: 8e1186475f87c928e8a146d3804d9a2697246ad0 192.168.37.131:7003
       slots:11256-16383 (5128 slots) master
       1 additional replica(s)
    M: 80de7003738f74134a3403fc939fed253b7774f2 192.168.37.131:7004
       slots:333-5460 (5128 slots) master
       1 additional replica(s)
    S: 652caf5daf7971135679951324eba7b50e99251a 192.168.37.131:7005
       slots: (0 slots) slave
       replicates 3adba62fdcc331ce231ca580cd2c8701e047bc6d
    M: 3adba62fdcc331ce231ca580cd2c8701e047bc6d 192.168.37.131:7002
       slots:5795-10922 (5128 slots) master
       1 additional replica(s)
    S: cf23ca6d78cba3d3924065e1f7a394f6c51d4b28 192.168.37.131:7006
       slots: (0 slots) slave
       replicates 8e1186475f87c928e8a146d3804d9a2697246ad0
    M: 5d6c61ecff23bff3b0fb01a86c66d882f2d402a0 192.168.37.131:7007
       slots:0-332,5461-5794,10923-11255 (1000 slots) master
       0 additional replica(s)
    [OK] All nodes agree about slots configuration.
    >>> Check for open slots...
    >>> Check slots coverage...
    [OK] All 16384 slots covered.
    Connecting to node 192.168.37.131:7008: OK
    >>> Send CLUSTER MEET to node 192.168.37.131:7008 to make it join the cluster.
    Waiting for the cluster to join.
    >>> Configure node as replica of 192.168.37.131:7007.
    [OK] New node added correctly.
    [root@localhost redis-cluster]#

`5d6c61ecff23bff3b0fb01a86c66d882f2d402a0`是`7007`结点的`id`，可以通过`cluster nodes`查看。

查看集群中的结点，刚添加的`7008`为`7007`的从节点：

[root@localhost redis-cluster]# ./redis1/redis-cli -p 7001 -c 127.0.0.1:7001> cluster nodes
    8e1186475f87c928e8a146d3804d9a2697246ad0 192.168.37.131:7003 master - 0 1478089964769 3 connected 11256-16383
    80de7003738f74134a3403fc939fed253b7774f2 192.168.37.131:7004 master - 0 1478089966584 8 connected 333-5460
    652caf5daf7971135679951324eba7b50e99251a 192.168.37.131:7005 slave 3adba62fdcc331ce231ca580cd2c8701e047bc6d 0 1478089963748 9 connected
    1cd6482fd7038d78ad556b52b0cb9e2590ad5598 192.168.37.131:7001 myself,slave 80de7003738f74134a3403fc939fed253b7774f2 0 0 1 connected
    3adba62fdcc331ce231ca580cd2c8701e047bc6d 192.168.37.131:7002 master - 0 1478089966787 9 connected 5795-10922
    cf23ca6d78cba3d3924065e1f7a394f6c51d4b28 192.168.37.131:7006 slave 8e1186475f87c928e8a146d3804d9a2697246ad0 0 1478089962729 6 connected
    5c97e8eab019c40ea3df4925c7400fe7df1846bb 192.168.37.131:7008 slave 5d6c61ecff23bff3b0fb01a86c66d882f2d402a0 0 1478089961713 10 connected
    5d6c61ecff23bff3b0fb01a86c66d882f2d402a0 192.168.37.131:7007 master - 0 1478089965777 10 connected 0-332 5461-5794 10923-11255
    127.0.0.1:7001>

#### 删除结点 ####

./redis-trib.rb del-node 192.168.37.131:7007 5d6c61ecff23bff3b0fb01a86c66d882f2d402a0

删除已经占有`hash`槽的结点会失败，报错如下：

[ERR] Node 192.168.37.131:7007 is not empty! Reshard data away and try again.

需要将该结点占用的`hash`槽分配出去，请参考《hash槽重新分配》这段内容。

### 客户端对Redis集群的使用方法 ###

#### 使用redis命令行客户端连接 ####

[root@localhost redis-cluster]# ./redis1/redis-cli -p 7001 -c
    127.0.0.1:7001> get a
    -> Redirected to slot [15495] located at 192.168.37.131:7003
    (nil)
    192.168.37.131:7003>

一定要加`-c`参数,节点之间就可以互相跳转

#### 使用jedis连接 ####

package com.pc.jedis.test;
    
    import java.util.HashSet;
    import java.util.Set;
    
    import redis.clients.jedis.HostAndPort;
    import redis.clients.jedis.JedisCluster;
    
    /** * Jedis集群测试 * * @author Switch * @data 2017年2月11日 * @version V1.0 */
    public class JedisClusterTest { 
        public static void main(String[] args) {
            // 创建并填充节点信息
            Set<HostAndPort> nodes = new HashSet<>();
            nodes.add(new HostAndPort("192.168.37.131", 7001));
            nodes.add(new HostAndPort("192.168.37.131", 7002));
            nodes.add(new HostAndPort("192.168.37.131", 7003));
            nodes.add(new HostAndPort("192.168.37.131", 7004));
            nodes.add(new HostAndPort("192.168.37.131", 7005));
            nodes.add(new HostAndPort("192.168.37.131", 7006));
    
            // 创建JedisCluster对象
            JedisCluster jedisCluster = new JedisCluster(nodes);
    
            // 使用jedisCluster操作redis
            String key = "jedisCluster";
            String setResult = jedisCluster.set(key, "hello redis!");
            System.out.println(setResult);
    
            String getResult = jedisCluster.get(key);
            System.out.println(getResult);
    
            // 关闭jedisCluster（程序执行完后才能关闭，内部封装了连接池）
            jedisCluster.close();
        }
    }

——参考《Redis官方文档》

[redis-cluster]: /images/20220711/7097fab1aef64cafa467eb5b06617605.png
[redis-cluster 1]: /images/20220711/ed22426112bf4fc2ba326ec844f99b55.png