一、环境准备：

角色	Ip地址	主机名	端口
Redis服务器（master）	Host58	192.168.88.58	6379
Redis服务器（slave）	Host59	192.168.88.59	6379

二、添加流程思路：

准备要添加redis服务器并做好集群配置
配置管理主机mgm57
添加Master服务器到集群
添加slave服务器到集群

第一步：准备要添加redis服务器并做好集群配置

准备redis服务器Host58（作为master加入到集群）

[root@host58 ~]# yum -y install gcc 
[root@host58 ~]# tar -xf redis-4.0.8.tar.gz 
[root@host58 ~]# cd redis-4.0.8/
[root@host58 ~]# make && make install
[root@host58 ~]# ./utils/install_server.sh  遇到提示就回车

# 配置58启用集群功能
[root@host58 ~]# /etc/init.d/redis_6379  stop
[root@host58 ~]# sed -n '70p;93p;815p;823p;829p' /etc/redis/6379.conf 
[root@host58 ~]# vim /etc/redis/6379.conf 
bind 192.168.88.58 
port 6379
cluster-enabled yes #启用集群功能
cluster-config-file nodes-6379.conf 保存集群信息的配置文件
cluster-node-timeout 5000  集群中主机的连接超时时间
           
[root@host58 ~]# /etc/init.d/redis_6379  restart
[root@host58 ~]# netstat  -utnlp  | grep redis-server
tcp   0      0 192.168.88.58:16379   0.0.0.0:*   LISTEN      4249/redis-server 1 
tcp  0    0 192.168.88.58:6379      0.0.0.0:*   LISTEN      4249/redis-server 1

准备redis服务器Host59（作为slave加入到集群）

[root@host59 ~]# yum -y install gcc 
[root@host59 ~]# tar -xf redis-4.0.8.tar.gz 
[root@host59 ~]# cd redis-4.0.8/
[root@host59 ~]# make && make install
[root@host59 ~]# ./utils/install_server.sh  遇到提示就回车

# 在host59 主机运行redis服务 且启用了集群功能
[root@host59 ~]# /etc/init.d/redis_6379  stop
[root@host59 ~]# sed -n '70p;93p;815p;823p;829p' /etc/redis/6379.conf 
[root@host59 ~]# vim /etc/redis/6379.conf 
bind 192.168.88.59 
port 6379
cluster-enabled yes # 启用集群功能
cluster-config-file nodes-6379.conf # 保存集群信息的配置文件
cluster-node-timeout 5000  # 集群中主机的连接超时时间
# 重启服务生效配置
[root@host59 ~]# /etc/init.d/redis_6379  restart
[root@host59 ~]# netstat  -utnlp  | grep redis-server
tcp        0      0 192.168.88.59:16379      0.0.0.0:*               LISTEN      4249/redis-server 1 
tcp        0      0 192.168.88.59:6379      0.0.0.0:*               LISTEN      4249/redis-server 1

第二步：配置管理主机mgm57

添加58服务器到集群（作为Master加入）

[root@mgm57 ~]# redis-trib.rb add-node 192.168.88.58:6379 192.168.88.51:6379
.....
.....
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
>>> Send CLUSTER MEET to node 192.168.88.58:6379 to make it join the cluster.
[OK] New node added correctly.  添加成功的提示

# 新添加的master角色主机没有hash slots
[root@mgm57 ~]# redis-trib.rb info  192.168.88.51:6379
192.168.88.51:6379 (0eb3b7aa...) -> 2 keys | 5461 slots | 1 slaves.
192.168.88.53:6379 (f2c1bdb7...) -> 1 keys | 5461 slots | 1 slaves.
192.168.88.52:6379 (a9cb8ccd...) -> 3 keys | 5462 slots | 1 slaves.
192.168.88.58:6379 (87cc1c12...) -> 0 keys | 0 slots | 0 slaves.   零个hash slots 
[OK] 6 keys in 4 masters.
0.00 keys per slot on average.

分配hast slots
master角色的服务器没有hast slots得不到存储数据机会

[root@mgm57 ~]# redis-trib.rb reshard  192.168.88.56:6379
# 第1个问题 移除多少个hast slots
How many slots do you want to move (from 1 to 16384)? 4096
# 第2个问题 把4096个槽给哪台主数据库服务器 (host58主机的id) 
What is the receiving node ID?87cc1c128166e08a16cc294758611453bbc71437 
# 第3个问题 提供4096个槽 主机的id (all 表示当前所有主服务器一起提供4096个槽给host58)
Source node #1:all
# 第4个问题 确认前3步的配置 yes 同意 no  退出
Do you want to proceed with the proposed reshard plan (yes/no)? yes

查看集群信息（查看到多新的主服务器且有hast slots 为成功）

[root@mgm57 ~]# redis-trib.rb info  192.168.88.56:6379
192.168.88.53:6379 (f2c1bdb7...) -> 1 keys | 4096 slots | 1 slaves.
192.168.88.51:6379 (0eb3b7aa...) -> 1 keys | 4096 slots | 1 slaves.
192.168.88.52:6379 (a9cb8ccd...) -> 2 keys | 4096 slots | 1 slaves.
192.168.88.58:6379 (87cc1c12...) -> 2 keys | 4096 slots | 0 slaves.
[OK] 6 keys in 4 masters.
0.00 keys per slot on average.
[root@mgm57 ~]# 
                        #具体查看host58 占用4096个槽的范围
[root@mgm57 ~]# redis-trib.rb check  192.168.88.56:6379
....
....                        
M: 87cc1c128166e08a16cc294758611453bbc71437 192.168.88.58:6379
   slots:0-1364,5461-6826,10923-12287 (4096 slots) master
   0 additional replica(s)

添加59服务器到集群（作为Slave加入）
添加的从服务器会自动做从服务器个数最少的 master服务器的从服务器

# --slave：作为从服务器被添加到集群
[root@mgm57 ~]# redis-trib.rb add-node --slave 192.168.88.59:6379  192.168.88.56:6379
....
....
[OK] All 16384 slots covered.
Automatically selected master 192.168.88.58:6379
>>> Send CLUSTER MEET to node 192.168.88.59:6379 to make it join the cluster.
Waiting for the cluster to join.
>>> Configure node as replica of 192.168.88.58:6379.
[OK] New node added correctly.

[root@mgm57 ~]# redis-trib.rb info  192.168.88.56:6379
192.168.88.53:6379 (f2c1bdb7...) -> 1 keys | 4096 slots | 1 slaves.
192.168.88.51:6379 (0eb3b7aa...) -> 1 keys | 4096 slots | 1 slaves.
192.168.88.52:6379 (a9cb8ccd...) -> 2 keys | 4096 slots | 1 slaves.
192.168.88.58:6379 (87cc1c12...) -> 2 keys | 4096 slots | 1 slaves.  host58主机的从
[OK] 6 keys in 4 masters.
0.00 keys per slot on average.

查看集群详细信息

[root@mgm57 ~]# redis-trib.rb check  192.168.88.56:6379
....
.....
S: d50aa7c1acebe69af0834f1838c8b17b2348472e 192.168.88.59:6379
   slots: (0 slots) slave
   replicates 87cc1c128166e08a16cc294758611453bbc71437    主服务器的id 

# 连接host59 查看数据     
[root@host56 ~]# redis-cli  -c  -h 192.168.88.59 -p 6379  
192.168.88.59:6379> keys *
1) "name"
2) "age"
192.168.88.59:6379>