1.什么是Redis Cluster
1.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）
2.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。（使用ack协议）
3.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。
4.Redis集群有将数据自动切分（split）到多个节点的能力。
2.Redis Cluster的特点
#高性能:
1.在多分片节点中，将16384个槽位，均匀分布到多个分片节点中
2.存数据时，将key做crc16（key），然后和16384进行取模，得出槽位值（0-16384之间）
3.根据计算得出的槽位值，找到相对应的分片节点的主节点，存储到相应槽位上
4.如果客户端当时连接的节点不是将来要存储的分片节点，分片集群会将客户端连接切换至真正存储节点进行数据存储
5.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
6.Redis Cluster解决了redis资源利用率的问题
#高可用
7.在搭建集群时，会为每一个分片的主节点，对应一个从节点，实现slaveof功能，同时当主节点down，实现类似于sentinel的自动failover的功能。
3.槽的概念
1.在集群中，会把所有节点分为16384个槽位
2.槽位的序号是 0 - 16383，序号不重要，数量才重要
3.每一个槽位分配到数据的概率是一样
4.redis故障转移
1.在集群里面，节点会对其他节点进行下线检测。
2.当一个主节点下线时，集群里面的其他主节点负责对下线主节点进行故障移。
3.换句话说，集群的节点集成了下线检测和故障转移等类似 Sentinel 的功能。
五、redis集群搭建
1.环境准备
| 节点 |
IP |
端口 |
| 节点1 |
172.16.1.20 |
6379,6380 |
| 节点2 |
172.16.1.21 |
6379,6380 |
| 节点3 |
172.16.1.22 |
6379,6380 |
2.搭建redis
#删除以前的redis数据
rm -rf /service/redis/*
#创建多实例目录
mkdir /service/redis/{6379,6380} -p
mkdir /service/redis/{6379,6380} -p
mkdir /service/redis/{6379,6380} -p
#配置所有redis
vim /service/redis/6379/redis.conf
bind 172.16.1.20 127.0.0.1
port 6379
daemonize yes
pidfile /service/redis/6379/redis.pid
loglevel notice
logfile /service/redis/6379/redis.log
dbfilename dump.rdb
dir /service/redis/6379
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
vim /service/redis/6380/redis.conf
bind 172.16.1.20 127.0.0.1
port 6380
daemonize yes
pidfile /service/redis/6380/redis.pid
loglevel notice
logfile /service/redis/6380/redis.log
dbfilename dump.rdb
dir /service/redis/6380
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
3.启动所有redis
redis-server /service/redis/6379/redis.conf
redis-server /service/redis/6380/redis.conf
redis-server /service/redis/6379/redis.conf
redis-server /service/redis/6380/redis.conf
redis-server /service/redis/6379/redis.conf
redis-server /service/redis/6380/redis.conf
4.关联所有redis节点
1）登录所有节点
redis-cli -h 172.16.1.20 -p 6379
redis-cli -h 172.16.1.20 -p 6380
redis-cli -h 172.16.1.21 -p 6379
redis-cli -h 172.16.1.21 -p 6380
redis-cli -h 172.16.1.22 -p 6379
redis-cli -h 172.16.1.22 -p 6380
2）查看集群节点
#查看集群节点，每一各节点只能看到自己
172.16.1.20:6379> CLUSTER NODES
28faba09f4c0ec8cdb90d92e09636796427b7143 :6379 myself,master - 0 0 0 connected
3）关联所有节点
172.16.1.20:6379> CLUSTER MEET 172.16.1.20 6380
OK
172.16.1.20:6379> CLUSTER MEET 172.16.1.21 6379
OK
172.16.1.20:6379> CLUSTER MEET 172.16.1.21 6380
OK
172.16.1.20:6379> CLUSTER MEET 172.16.1.22 6379
OK
172.16.1.20:6379> CLUSTER MEET 172.16.1.22 6380
OK
#查看集群状态，所有节点
127.0.0.1:6379> CLUSTER NODES
a8f6b2c158962933711fd9d4288a961e01b64d3a 172.16.1.20:6379 myself,master - 0 0 2 connected
dec0b1ce2fc95e2e15caf870426d698eaf5b62ef 172.16.1.22:6380 master - 0 1596815903806 0 connected
2d1d8f2ab96748faf86c569b432eb997261f4a15 172.16.1.22:6379 master - 0 1596815902798 4 connected
47e4898f8dd357acfd3f8c478e145b4cddfa5fcf 172.16.1.20:6380 master - 0 1596815903300 1 connected
78b180ca5dbbba978a6be6ffb0559c7f322bbc9f 172.16.1.21:6380 master - 0 1596815902296 3 connected
f886c1b6f9b20a318825a6c32ebbf4e2acc68907 172.16.1.21:6379 master - 0 1596815901792 0 connected
5.分配槽位
#查看集群状态
127.0.0.1:6379> CLUSTER INFO
cluster_state:fail
cluster_slots_assigned:0
cluster_slots_ok:0
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:6
cluster_size:0
cluster_current_epoch:5
cluster_my_epoch:2
cluster_stats_messages_sent:783
cluster_stats_messages_received:743
#槽位规划
jojo01: 5462 个槽位 （0-5461）
jojo02: 5461 个槽位 （5462-10922）
jojo03: 5461 个槽位 （10923-16383）
#分配槽位
redis-cli -p 6379 -h 172.16.1.20 CLUSTER ADDSLOTS {0..5461}
OK
redis-cli -p 6379 -h 172.16.1.21 CLUSTER ADDSLOTS {5462..10922}
OK
redis-cli -p 6379 -h 172.16.1.22 CLUSTER ADDSLOTS {10923..16383}
6.插入数据测试集群
#ASK协议，-c 自动切换将数据添加到指定槽位
redis-cli -h 172.16.1.22
172.16.1.22:6379> set k2 v2
(error) MOVED 449 172.16.1.51:6379
172.16.1.53:6379> quit
redis-cli -c -h 172.16.1.22
172.16.1.22:6379> set k2 v2
-> Redirected to slot [449] located at 172.16.1.20:6379
OK
#脚本插入数据测试
vim data.sh
#!/bin/bash
for i in {1..1000};do
redis-cli -c -p 6379 -h 172.16.1.20 set k${i} v${i}
done
#查看数据分配
172.16.1.20:6379> DBSIZE
(integer) 341
172.16.1.21:6379> DBSIZE
(integer) 332
172.16.1.22:6379> DBSIZE
(integer) 327
7.添加副本节点
# 查看节点
172.16.1.20:6379> CLUSTER NODES
5a7f0cf95e1850b5b5ae81d873c4c76fd366d604 172.16.1.20:6380
5eb9e5356534ff4acda736d13f0dc9fc3d40049b 172.16.1.21:6379
50878ef6a4d8141c8dbca3e2bf7c84ed48a73ee2 172.16.1.22:6380
acc3a4d0e6e43fc74630c1f0714865fdcbdaf677 172.16.1.22:6379
2325be6f1f9c1c9f57d5a033fc05e0d798ea823a 172.16.1.20:6379
381b54584572e8013becdae2eeaff48bf6eb5450 172.16.1.21:6380
# 配置主从
1.jojo01 的6380做jojo02的6379的从库
[root@jojo ~]# redis-cli -h 172.16.1.20 -p 6380
172.16.1.20:6380> CLUSTER REPLICATE f886c1b6f9b20a318825a6c32ebbf4e2acc68907
2. jojo02的6380做jojo03的6379的从库
[root@jojo ~]# redis-cli -h 172.16.1.21 -p 6380
172.16.1.21:6380> CLUSTER REPLICATE 2d1d8f2ab96748faf86c569b432eb997261f4a15
OK
3. jojo03的6380做jojo01的6379的从库
[root@jojo ~]# redis-cli -h 172.16.1.22 -p 6380
172.16.1.22:6380> CLUSTER REPLICATE a8f6b2c158962933711fd9d4288a961e01b64d3a
OK
# 查看集群状态
127.0.0.1:6379> CLUSTER NODES
a8f6b2c158962933711fd9d4288a961e01b64d3a 172.16.1.20:6379 myself,master
dec0b1ce2fc95e2e15caf870426d698eaf5b62ef 172.16.1.22:6380 slave
2d1d8f2ab96748faf86c569b432eb997261f4a15 172.16.1.22:6379 master
47e4898f8dd357acfd3f8c478e145b4cddfa5fcf 172.16.1.20:6380 slave
78b180ca5dbbba978a6be6ffb0559c7f322bbc9f 172.16.1.21:6380 slave
f886c1b6f9b20a318825a6c32ebbf4e2acc68907 172.16.1.21:6379 master
8.故障演示
#停掉一台节点
[root@db03 ~]# reboot
#到另一台机器查看集群状态，发现集群是正常的
172.16.1.51:6379> 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:6
cluster_my_epoch:1
cluster_stats_messages_sent:327031
cluster_stats_messages_received:326973
#查看节点信息，副本被提升为主库
172.16.1.51:6379> CLUSTER NODES
5a7f0cf95e1850b5b5ae81d873c4c76fd366d604 172.16.1.51:6380 slave
5eb9e5356534ff4acda736d13f0dc9fc3d40049b 172.16.1.52:6379 master
50878ef6a4d8141c8dbca3e2bf7c84ed48a73ee2 172.16.1.53:6380 slave,fail
acc3a4d0e6e43fc74630c1f0714865fdcbdaf677 172.16.1.53:6379 master,fail
2325be6f1f9c1c9f57d5a033fc05e0d798ea823a 172.16.1.51:6379 myself,master
381b54584572e8013becdae2eeaff48bf6eb5450 172.16.1.52:6380 master # 提升为主库
# 节点恢复
#修复机器
[root@db03 ~]# redis-server /service/redis/6379/redis.conf
[root@db03 ~]# redis-server /service/redis/6380/redis.conf
#再次查看节点信息
172.16.1.51:6379> CLUSTER NODES
5a7f0cf95e1850b5b5ae81d873c4c76fd366d604 172.16.1.51:6380 slave
5eb9e5356534ff4acda736d13f0dc9fc3d40049b 172.16.1.52:6379 master
50878ef6a4d8141c8dbca3e2bf7c84ed48a73ee2 172.16.1.53:6380 slave # 恢复机器
acc3a4d0e6e43fc74630c1f0714865fdcbdaf677 172.16.1.53:6379 slave # 恢复机器
2325be6f1f9c1c9f57d5a033fc05e0d798ea823a 172.16.1.51:6379 myself,master
381b54584572e8013becdae2eeaff48bf6eb5450 172.16.1.52:6380 master
#原主节点修复后变为从节点
六、使用工具搭建redis集群
1.环境准备
| 节点 |
IP |
端口 |
| 节点1 |
172.16.1.51 |
6379,6380 |
| 节点2 |
172.16.1.52 |
6379,6380 |
| 节点3 |
172.16.1.53 |
6379,6380 |
2.搭建redis
3.启动所有redis
4.安装集群插件
#EPEL源安装ruby支持
[root@db01 ~]# yum install ruby rubygems -y
#查看gem源
[root@db01 ~]# gem sources -l
*** CURRENT SOURCES ***
http://rubygems.org/
#添加阿里云的gem源
[root@db01 ~]# gem sources -a http://mirrors.aliyun.com/rubygems/
http://mirrors.aliyun.com/rubygems/ added to sources
#删除国外gem源
[root@db01 ~]# gem sources --remove https://rubygems.org/
http://rubygems.org/ removed from sources
#再次查看gem源
[root@db01 ~]# gem sources -l
#使用gem安装redis的ruby插件
[root@db01 ~]# gem install redis -v 3.3.3
Successfully installed redis-3.3.3
1 gem installed
Installing ri documentation for redis-3.3.3...
Installing RDoc documentation for redis-3.3.3...
5. redis-trib.rb命令
[root@db01 ~]# redis-trib.rb
create #创建一个集群
check #检查集群
info #集群状态
fix #修复集群
reshard #重新分配槽位
rebalance #平衡槽位数量
add-node #添加节点
del-node #删除节点
set-timeout #设置超时时间
call #向集群所有机器输入命令
import #导入数据
help #帮助
6.关联所有节点
[root@db01 ~]# redis-trib.rb create --replicas 1 172.16.1.51:6379 172.16.1.52:6379 172.16.1.53:6379 172.16.1.52:6380 172.16.1.53:6380 172.16.1.51:6380
>>> Creating cluster
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
172.16.1.51:6379
172.16.1.52:6379
172.16.1.53:6379
Adding replica 172.16.1.52:6380 to 172.16.1.51:6379
Adding replica 172.16.1.51:6380 to 172.16.1.52:6379
Adding replica 172.16.1.53:6380 to 172.16.1.53:6379
M: 5ad7bd957133eac9c3a692b35f8ae72258cf0ece 172.16.1.51:6379
slots:0-5460 (5461 slots) master
M: 7c79559b280db9d9c182f3a25c718efe9e934fc7 172.16.1.52:6379
slots:5461-10922 (5462 slots) master
M: d27553035a3e91c78d375208c72b756e9b2523d4 172.16.1.53:6379
slots:10923-16383 (5461 slots) master
S: fee551a90c8646839f66fa0cd1f6e5859e9dd8e0 172.16.1.52:6380
replicates 5ad7bd957133eac9c3a692b35f8ae72258cf0ece
S: e4794215d9d3548e9c514c10626ce618be19ebfb 172.16.1.53:6380
replicates d27553035a3e91c78d375208c72b756e9b2523d4
S: 1d10edbc5ed08f85d2afc21cd338b023b9dd61b4 172.16.1.51:6380
replicates 7c79559b280db9d9c182f3a25c718efe9e934fc7
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 172.16.1.51:6379)
M: 5ad7bd957133eac9c3a692b35f8ae72258cf0ece 172.16.1.51:6379
slots:0-5460 (5461 slots) master
1 additional replica(s)
S: e4794215d9d3548e9c514c10626ce618be19ebfb 172.16.1.53:6380
slots: (0 slots) slave
replicates d27553035a3e91c78d375208c72b756e9b2523d4
M: d27553035a3e91c78d375208c72b756e9b2523d4 172.16.1.53:6379
slots:10923-16383 (5461 slots) master
1 additional replica(s)
S: fee551a90c8646839f66fa0cd1f6e5859e9dd8e0 172.16.1.52:6380
slots: (0 slots) slave
replicates 5ad7bd957133eac9c3a692b35f8ae72258cf0ece
S: 1d10edbc5ed08f85d2afc21cd338b023b9dd61b4 172.16.1.51:6380
slots: (0 slots) slave
replicates 7c79559b280db9d9c182f3a25c718efe9e934fc7
M: 7c79559b280db9d9c182f3a25c718efe9e934fc7 172.16.1.52:6379
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.查看集群状态
[root@db01 ~]# redis-cli -h 172.16.1.51 -p 6379 CLUSTER NODES
e4794215d9d3548e9c514c10626ce618be19ebfb 172.16.1.53:6380 slave d27553035a3e91c78d375208c72b756e9b2523d4 0 1596767315453 5 connected
d27553035a3e91c78d375208c72b756e9b2523d4 172.16.1.53:6379 master - 0 1596767315453 3 connected 10923-16383
5ad7bd957133eac9c3a692b35f8ae72258cf0ece 172.16.1.51:6379 myself,master - 0 0 1 connected 0-5460
fee551a90c8646839f66fa0cd1f6e5859e9dd8e0 172.16.1.52:6380 slave 5ad7bd957133eac9c3a692b35f8ae72258cf0ece 0 1596767313429 4 connected
1d10edbc5ed08f85d2afc21cd338b023b9dd61b4 172.16.1.51:6380 slave 7c79559b280db9d9c182f3a25c718efe9e934fc7 0 1596767313935 6 connected
7c79559b280db9d9c182f3a25c718efe9e934fc7 172.16.1.52:6379 master - 0 1596767314949 2 connected 5461-10922
8.重新做主从
#由于使用工具，始终有一台机器从库本机的从库，所以要重新分配主从
172.16.1.52:6380> CLUSTER REPLICATE d27553035a3e91c78d375208c72b756e9b2523d4
OK
172.16.1.53:6380> CLUSTER REPLICATE 5ad7bd957133eac9c3a692b35f8ae72258cf0ece
OK
9.插入数据测试
[root@db01 ~]# redis-trib.rb info 172.16.1.52:6379
172.16.1.52:6379 (7c79559b...) -> 332 keys | 5462 slots | 1 slaves.
172.16.1.51:6379 (5ad7bd95...) -> 341 keys | 5461 slots | 1 slaves.
172.16.1.53:6379 (d2755303...) -> 327 keys | 5461 slots | 1 slaves.
[OK] 1000 keys in 3 masters.
0.06 keys per slot on average.
[root@db01 ~]# redis-trib.rb info 172.16.1.52:6379
172.16.1.52:6379 (7c79559b...) -> 661 keys | 5462 slots | 1 slaves.
172.16.1.51:6379 (5ad7bd95...) -> 674 keys | 5461 slots | 1 slaves.
172.16.1.53:6379 (d2755303...) -> 665 keys | 5461 slots | 1 slaves.
[OK] 2000 keys in 3 masters.
0.12 keys per slot on average.
七、redis集群节点修改
#添加和删除节点的流程
1.新节点添加槽位
2.源节点中的数据进行迁移
3.源节点数据迁移完毕
4.迁移下一个槽位的数据，依次循环
1.添加节点
1）准备新机器
[root@db02 ~]# mkdir /service/redis/{6381,6382}
[root@db02 ~]# vim /service/redis/6381/redis.conf
[root@db02 ~]# vim /service/redis/6382/redis.conf
#启动新节点
[root@db02 ~]# redis-server /service/redis/6381/redis.conf
[root@db02 ~]# redis-server /service/redis/6382/redis.conf
2）将新节点添加到集群
[root@db01 ~]# redis-trib.rb add-node 172.16.1.52:6381 172.16.1.51:6379
#或者
[root@db01 ~]# redis-cli -p 6379 -h 172.16.1.51 cluster meet 172.16.1.52:6381
#查看节点信息
[root@db01 ~]# redis-trib.rb info 172.16.1.51:6379
[root@db01 ~]# redis-cli -p 6379 -h 172.16.1.51 cluster nodes
3）重新分配槽位
[root@db01 ~]# redis-trib.rb reshard 172.16.1.51:6379
#你想移动多少个槽位到新节点
How many slots do you want to move (from 1 to 16384)? 4096
#新节点的ID是什么
What is the receiving node ID? a298dbd22c10b8492d9ff4295504c50666f4fb2e
#输入源节点的ID，如果是所有节点直接使用all
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：all
#你确定要这么分配？
Do you want to proceed with the proposed reshard plan (yes/no)? yes
#分配完毕，查看分配结果
[root@db01 ~]# redis-cli -p 6379 -h 172.16.1.51 cluster nodes
e4794215d9d3548e9c514c10626ce618be19ebfb 172.16.1.53:6380 slave 5ad7bd957133eac9c3a692b35f8ae72258cf0ece 0 1596769469815 5 connected
d27553035a3e91c78d375208c72b756e9b2523d4 172.16.1.53:6379 master - 0 1596769468805 3 connected 12288-16383
5ad7bd957133eac9c3a692b35f8ae72258cf0ece 172.16.1.51:6379 myself,master - 0 0 1 connected 1365-5460
fee551a90c8646839f66fa0cd1f6e5859e9dd8e0 172.16.1.52:6380 slave d27553035a3e91c78d375208c72b756e9b2523d4 0 1596769467797 4 connected
1d10edbc5ed08f85d2afc21cd338b023b9dd61b4 172.16.1.51:6380 slave 7c79559b280db9d9c182f3a25c718efe9e934fc7 0 1596769469513 6 connected
a298dbd22c10b8492d9ff4295504c50666f4fb2e 172.16.1.52:6381 master - 0 1596769468302 7 connected 0-1364 5461-6826 10923-12287
7c79559b280db9d9c182f3a25c718efe9e934fc7 172.16.1.52:6379 master - 0 1596769468302 2 connected 6827-10922
[root@db01 ~]#
[root@db01 ~]# redis-trib.rb info 172.16.1.51:6379
172.16.1.51:6379 (5ad7bd95...) -> 499 keys | 4096 slots | 1 slaves.
172.16.1.53:6379 (d2755303...) -> 501 keys | 4096 slots | 1 slaves.
172.16.1.52:6381 (a298dbd2...) -> 502 keys | 4096 slots | 0 slaves.
172.16.1.52:6379 (7c79559b...) -> 498 keys | 4096 slots | 1 slaves.
[OK] 2000 keys in 4 masters.
0.12 keys per slot on average.
4）添加新节点的副本
[root@db02 ~]# redis-cli -h 172.16.1.52 -p 6382 cluster replicate a298dbd22c10b8492d9ff4295504c50666f4fb2e
#或者
[root@db01 ~]# redis-trib.rb add-node --slave --master-id a298dbd22c10b8492d9ff4295504c50666f4fb2e 172.16.1.52:6382 172.16.1.51:6379
（集群中任意一台机器）
[root@db01 ~]# redis-cli -p 6379 -h 172.16.1.51 cluster nodes
[root@db01 ~]# redis-trib.rb info 172.16.1.51:6379
172.16.1.51:6379 (5ad7bd95...) -> 499 keys | 4096 slots | 1 slaves.
172.16.1.53:6379 (d2755303...) -> 501 keys | 4096 slots | 1 slaves.
172.16.1.52:6381 (a298dbd2...) -> 502 keys | 4096 slots | 1 slaves.
172.16.1.52:6379 (7c79559b...) -> 498 keys | 4096 slots | 1 slaves.
[OK] 2000 keys in 4 masters.
0.12 keys per slot on average.
#调整主从，尽量保证每一台机器的副本都不于主节点在一台机器
5）模拟故障
#分配槽位的过程中
[root@db01 ~]# redis-trib.rb reshard 172.16.1.51:6379
#执行Ctrl+c
#查看集群状态一些命令看不出来有错
[root@db01 ~]# redis-cli -p 6379 -h 172.16.1.51 cluster info
[root@db01 ~]# redis-cli -p 6379 -h 172.16.1.51 cluster nodes
[root@db01 ~]# redis-trib.rb info 172.16.1.51:6379
#必须使用工具检查集群
[root@db01 ~]# redis-trib.rb check 172.16.1.51:6379
#错误一：172.16.1.52:6379节点正在导出槽位，172.16.1.52:6381节点正在导入槽位
>>> Check for open slots...
[WARNING] Node 172.16.1.52:6381 has slots in importing state (6885).
[WARNING] Node 172.16.1.52:6379 has slots in migrating state (6885).
[WARNING] The following slots are open: 6885
>>> Check slots coverage...
#错误二：172.16.1.52:6379节点正在导出槽位
>>> Check for open slots...
[WARNING] Node 172.16.1.52:6379 has slots in migrating state (6975).
[WARNING] The following slots are open: 6975
>>> Check slots coverage...
#错误三：
>>> Check for open slots...
[WARNING] Node 172.16.1.52:6381 has slots in importing state (7093).
[WARNING] The following slots are open: 7093
>>> Check slots coverage...
6）修复故障
#使用fix修复集群
[root@db01 ~]# redis-trib.rb fix 172.16.1.52:6379
#将槽位平均分配
1.平均之前
[root@db01 ~]# redis-trib.rb info 172.16.1.51:6379
172.16.1.51:6379 (5ad7bd95...) -> 499 keys | 4096 slots | 1 slaves.
172.16.1.53:6379 (d2755303...) -> 501 keys | 4096 slots | 1 slaves.
172.16.1.52:6381 (a298dbd2...) -> 648 keys | 5320 slots | 1 slaves.
172.16.1.52:6379 (7c79559b...) -> 352 keys | 2872 slots | 1 slaves.
[OK] 2000 keys in 4 masters.
0.12 keys per slot on average.
2.平均分配（如果节点之间槽位数量相差较小，不会平均分配）
[root@db01 ~]# redis-trib.rb rebalance 172.16.1.51:6379
>>> Performing Cluster Check (using node 172.16.1.51:6379)
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
>>> Rebalancing across 4 nodes. Total weight = 4
Moving 1224 slots from 172.16.1.52:6381 to 172.16.1.52:6379
#####################################################################################################
3平均分配之后
[root@db01 ~]# redis-trib.rb info 172.16.1.51:6379
172.16.1.51:6379 (5ad7bd95...) -> 499 keys | 4096 slots | 1 slaves.
172.16.1.53:6379 (d2755303...) -> 501 keys | 4096 slots | 1 slaves.
172.16.1.52:6381 (a298dbd2...) -> 492 keys | 4096 slots | 1 slaves.
172.16.1.52:6379 (7c79559b...) -> 508 keys | 4096 slots | 1 slaves.
[OK] 2000 keys in 4 masters.
0.12 keys per slot on average.
2.删除节点
1）重新分配槽位
#重新分配
[root@db01 ~]# redis-trib.rb reshard 172.16.1.51:6379
How many slots do you want to move (from 1 to 16384)? 1365 #要分配的槽位数量
What is the receiving node ID? #接收槽位的节点id
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: 要删除的节点id
Source node #2: done
Do you want to proceed with the proposed reshard plan (yes/no)? yes
#第二次重新分配
[root@db01 ~]# redis-trib.rb reshard 172.16.1.51:6379
How many slots do you want to move (from 1 to 16384)? 1365
What is the receiving node ID? 7c79559b280db9d9c182f3a25c718efe9e934fc7
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:a298dbd22c10b8492d9ff4295504c50666f4fb2e
Source node #2:done
Do you want to proceed with the proposed reshard plan (yes/no)? yes
#第三次重新分配
[root@db01 ~]# redis-trib.rb reshard 172.16.1.51:6379
How many slots do you want to move (from 1 to 16384)? 1366
What is the receiving node ID? d27553035a3e91c78d375208c72b756e9b2523d4
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:a298dbd22c10b8492d9ff4295504c50666f4fb2e
Source node #2:done
Do you want to proceed with the proposed reshard plan (yes/no)? yes
2）查看重新分配以后的节点信息
[root@db01 ~]# redis-trib.rb info 172.16.1.51:6379
172.16.1.51:6379 (5ad7bd95...) -> 664 keys | 5461 slots | 1 slaves.
172.16.1.53:6379 (d2755303...) -> 665 keys | 5462 slots | 2 slaves.
172.16.1.52:6381 (a298dbd2...) -> 0 keys | 0 slots | 0 slaves.
172.16.1.52:6379 (7c79559b...) -> 671 keys | 5461 slots | 1 slaves.
[OK] 2000 keys in 4 masters.
0.12 keys per slot on average.
3）删除节点
#删除没有数据的主节点
[root@db01 ~]# redis-trib.rb del-node 172.16.1.52:6381 a298dbd22c10b8492d9ff4295504c50666f4fb2e
>>> Removing node a298dbd22c10b8492d9ff4295504c50666f4fb2e from cluster 172.16.1.52:6381
>>> Sending CLUSTER FORGET messages to the cluster...
>>> SHUTDOWN the node.
#删除从节点
[root@db01 ~]# redis-trib.rb del-node 172.16.1.52:6382 47e3638a203488218d8c62deb82e768598977ba4
>>> Removing node 47e3638a203488218d8c62deb82e768598977ba4 from cluster 172.16.1.52:6382
>>> Sending CLUSTER FORGET messages to the cluster...
>>> SHUTDOWN the node.
#删除时不能删除有数据的主节点，从节点可以随便删除
[root@db01 ~]# redis-trib.rb del-node 172.16.1.53:6379 d27553035a3e91c78d375208c72b756e9b2523d4
>>> Removing node d27553035a3e91c78d375208c72b756e9b2523d4 from cluster 172.16.1.53:6379
[ERR] Node 172.16.1.53:6379 is not empty! Reshard data away and try again.
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