接近3w详解Docker搭建Redis集群（主从容错、主从扩容、主从缩容）

cluster(集群)模式-docker版 哈希槽分区进行亿级数据存储

1、场景

1~2亿条数据需要缓存，请问如何设计这个存储案例？

单机单台100%不可能，肯定是分布式存储，用redis如何落地？

解决方案

1、哈希取余分区

2亿条记录就是2亿个k,v，我们单机不行必须要分布式多机，假设有3台机器构成一个集群，用户每次读写操作都是根据公式：
hash(key) % N个机器台数，计算出哈希值，用来决定数据映射到哪一个节点上。

优点：

简单粗暴，直接有效，只需要预估好数据规划好节点，例如3台、8台、10台，就能保证一段时间的数据支撑。使用Hash算法让固定的一部分请求落到同一台服务器上，这样每台服务器固定处理一部分请求（并维护这些请求的信息），起到负载均衡+分而治之的作用。

缺点：

 原来规划好的节点，进行扩容或者缩容就比较麻烦了额，不管扩缩，每次数据变动导致节点有变动，映射关系需要重新进行计算，在服务器个数固定不变时没有问题，如果需要弹性扩容或故障停机的情况下，原来的取模公式就会发生变化：Hash(key)/3会变成Hash(key) /?。此时地址经过取余运算的结果将发生很大变化，根据公式获取的服务器也会变得不可控。
某个redis机器宕机了，由于台数数量变化，会导致hash取余全部数据重新洗牌。

2、一致性哈希算法分区

　　一致性哈希算法在1997年由麻省理工学院中提出的，设计目标是为了解决分布式缓存数据变动和映射问题，某个机器宕机了，分母数量改变了，自然取余数不OK了。

作用：

提出一致性Hash解决方案。目的是当服务器个数发生变动时，尽量减少影响客户端到服务器的映射关系

步骤：

1. 算法构建一致性哈希环

   一致性哈希环

   ​ 一致性哈希算法必然有个hash函数并按照算法产生hash值，这个算法的所有可能哈希值会构成一个全量集，这个集合可以成为一个hash空间[0,2^32-1]，这个是一个线性空间，但是在算法中，我们通过适当的逻辑控制将它首尾相连(0 = 2^32),这样让它逻辑上形成了一个环形空间。

   它也是按照使用取模的方法，前面笔记介绍的节点取模法是对节点（服务器）的数量进行取模。而一致性Hash算法是对2^32 取模，简单来说，一致性Hash算法将整个哈希值空间组织成一个虚拟的圆环，如假设某哈希函数H的值空间为0-2^32-1 （即哈希值是一个32位无符号整形），整个哈希环如下图：整个空间按顺时针方向组织，圆环的正上方的点代表0，0点右侧的第一个点代表1，以此类推，2、3、4、……直到2^32-1 ，也就是说0点左侧的第一个点代表2^32-1， 0和2^32-1 在零点中方向重合，我们把这个由2^32个点组成的圆环称为Hash环。

   

2. 服务器IP节点映射

   节点映射

   将集群中各个IP节点映射到环上的某一个位置。
   将各个服务器使用Hash进行一个哈希，具体可以选择服务器的IP或主机名作为关键字进行哈希，这样每台机器就能确定其在哈希环上的位置。假如4个节点NodeA、B、C、D，经过IP地址的哈希函数计算(hash(ip))，使用IP地址哈希后在环空间的位置如下：

3. key落到服务器的落键规则

   当我们需要存储一个kv键值对时，首先计算key的hash值，hash(key)，将这个key使用相同的函数Hash计算出哈希值并确定此数据在环上的位置，从此位置沿环顺时针“行走”，第一台遇到的服务器就是其应该定位到的服务器，并将该键值对存储在该节点上。
   如我们有Object A、Object B、Object C、Object D四个数据对象，经过哈希计算后，在环空间上的位置如下：根据一致性Hash算法，数据A会被定为到Node A上，B被定为到Node B上，C被定为到Node C上，D被定为到Node D上。

优点：

1.一致性哈希算法的容错性

容错性
假设Node C宕机，可以看到此时对象A、B、D不会受到影响，只有C对象被重定位到Node D。一般的，在一致性Hash算法中，如果一台服务器不可用，则受影响的数据仅仅是此服务器到其环空间中前一台服务器（即沿着逆时针方向行走遇到的第一台服务器）之间数据，其它不会受到影响。简单说，就是C挂了，受到影响的只是B、C之间的数据，并且这些数据会转移到D进行存储。

2.一致性哈希算法的扩展性

扩展性
数据量增加了，需要增加一台节点NodeX，X的位置在A和B之间，那收到影响的也就是A到X之间的数据，重新把A到X的数据录入到X上即可，不会导致hash取余全部数据重新洗牌。

缺点：

一致性哈希算法的数据倾斜问题

一致性Hash算法在服务节点太少时，容易因为节点分布不均匀而造成数据倾斜（被缓存的对象大部分集中缓存在某一台服务器上）问题，
例如系统中只有两台服务器：

总结：

为了在节点数目发生改变时尽可能少的迁移数据

将所有的存储节点排列在收尾相接的Hash环上，每个key在计算Hash后会顺时针找到临近的存储节点存放。
而当有节点加入或退出时仅影响该节点在Hash环上顺时针相邻的后续节点。

优点 加入和删除节点只影响哈希环中顺时针方向的相邻的节点，对其他节点无影响。

缺点 数据的分布和节点的位置有关，因为这些节点不是均匀的分布在哈希环上的，所以数据在进行存储时达不到均匀分布的效果。

3、哈希槽分区

哈希槽实质就是一个数组，数组[0,2^14 -1]形成hash slot空间。

作用：解决一致性哈希算法的数据倾斜问题

解决均匀分配的问题，在数据和节点之间又加入了一层，把这层称为哈希槽（slot），用于管理数据和节点之间的关系，现在就相当于节点上放的是槽，槽里放的是数据。

槽解决的是粒度问题，相当于把粒度变大了，这样便于数据移动。
哈希解决的是映射问题，使用key的哈希值来计算所在的槽，便于数据分配。

哈希槽的计算

Redis 集群中内置了 16384 个哈希槽，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。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，也就是映射到某个节点上。如下代码，key之A 、B在Node2， key之C落在Node3上

2、3主3从集群配置

1、启动docker

systemctl start docker

2、新建6个docker容器redis实例

docker run -d --name redis-node-1 --net host --privileged=true -v /data/redis/share/redis-node-1:/data redis --cluster-enabled yes --appendonly yes --port 6381
 
docker run -d --name redis-node-2 --net host --privileged=true -v /data/redis/share/redis-node-2:/data redis --cluster-enabled yes --appendonly yes --port 6382
 
docker run -d --name redis-node-3 --net host --privileged=true -v /data/redis/share/redis-node-3:/data redis --cluster-enabled yes --appendonly yes --port 6383
 
docker run -d --name redis-node-4 --net host --privileged=true -v /data/redis/share/redis-node-4:/data redis --cluster-enabled yes --appendonly yes --port 6384
 
docker run -d --name redis-node-5 --net host --privileged=true -v /data/redis/share/redis-node-5:/data redis --cluster-enabled yes --appendonly yes --port 6385
 
docker run -d --name redis-node-6 --net host --privileged=true -v /data/redis/share/redis-node-6:/data redis --cluster-enabled yes --appendonly yes --port 6386

[root@docker ~]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS     NAMES
d6fc3ef2855b   redis     "docker-entrypoint.s…"   3 seconds ago   Up 2 seconds             redis-node-6
9c8868d69a50   redis     "docker-entrypoint.s…"   3 seconds ago   Up 3 seconds             redis-node-5
7fbb5345951a   redis     "docker-entrypoint.s…"   4 seconds ago   Up 3 seconds             redis-node-4
d53b9d5af1ac   redis     "docker-entrypoint.s…"   4 seconds ago   Up 4 seconds             redis-node-3
fe0e430cb940   redis     "docker-entrypoint.s…"   6 seconds ago   Up 4 seconds             redis-node-2
ee03a7ec212e   redis     "docker-entrypoint.s…"   8 seconds ago   Up 6 seconds             redis-node-1

分步解释

• docker run：创建并运行docker容器实例
• --name redis-node-6：容器名字
• --net host ：使用宿主机的IP和端口，默认、
• --privileged=true：获取宿主机root用户权限
• -v /data/redis/share/redis-node-6:/data：容器卷，宿主机地址:docker内部地址
• redis：redis镜像和版本号
• --cluster-enabled yes：开启redis集群
• --appendonly yes：开启持久化
• --port 6386：redis端口号

3、进入容器redis-node-1并为6台机器构建集群关系

1、进入容器

docker exec -it redis-node-1 /bin/bash

2、构建主从关系

PS：注意自己的真实IP地址

redis-cli --cluster create 192.168.130.132:6381 192.168.130.132:6382 192.168.130.132:6383 192.168.130.132:6384 192.168.130.132:6385 192.168.130.132:6386 --cluster-replicas 1

• --cluster-replicas 1：表示为每个master创建一个slave节点

[root@docker ~]# docker exec -it redis-node-1 /bin/bash
root@docker:/data# redis-cli --cluster create 192.168.130.132:6381 192.168.130.132:6382 192.168.130.132:6383 192.168.130.132:6384 192.168.130.132:6385 192.168.130.132:6386 --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 192.168.130.132:6385 to 192.168.130.132:6381
Adding replica 192.168.130.132:6386 to 192.168.130.132:6382
Adding replica 192.168.130.132:6384 to 192.168.130.132:6383
>>> Trying to optimize slaves allocation for anti-affinity
[WARNING] Some slaves are in the same host as their master
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[0-5460] (5461 slots) master
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[5461-10922] (5462 slots) master
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[10923-16383] (5461 slots) master
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
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 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[0-5460] (5461 slots) master
   1 additional replica(s)
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[10923-16383] (5461 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[5461-10922] (5462 slots) master
   1 additional replica(s)
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 

到这里，3主3从就构建完成了。

4、链接进入6381作为切入点，查看集群状态

root@docker:/data# redis-cli -p 6381
127.0.0.1:6381> 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_ping_sent:663
cluster_stats_messages_pong_sent:671
cluster_stats_messages_sent:1334
cluster_stats_messages_ping_received:666
cluster_stats_messages_pong_received:663
cluster_stats_messages_meet_received:5
cluster_stats_messages_received:1334
127.0.0.1:6381> cluster nodes
b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385@16385 slave 8dbe8b347410cf87d62933382b73693405535ba1 0 1651152474000 3 connected
8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381@16381 myself,master - 0 1651152472000 1 connected 0-5460
8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383@16383 master - 0 1651152474000 3 connected 10923-16383
c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384@16384 slave 60fa7e084483feca3af41f269de5a57b526c0ad7 0 1651152476585 2 connected
60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382@16382 master - 0 1651152475573 2 connected 5461-10922
4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386@16386 slave 8335b5349d781c11745ee129f5dbae370dbd3394 0 1651152474566 1 connected
127.0.0.1:6381> 

1、cluster info：查看集群状态

127.0.0.1:6381> 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_ping_sent:663
cluster_stats_messages_pong_sent:671
cluster_stats_messages_sent:1334
cluster_stats_messages_ping_received:666
cluster_stats_messages_pong_received:663
cluster_stats_messages_meet_received:5
cluster_stats_messages_received:1334

• cluster_state: ok状态表示集群可以正常接受查询请求。fail 状态表示，至少有一个哈希槽没有被绑定（说明有哈希槽没有被绑定到任意一个节点），或者在错误的状态（节点可以提供服务但是带有FAIL 标记），或者该节点无法联系到多数master节点。.
• cluster_slots_assigned: 已分配到集群节点的哈希槽数量（不是没有被绑定的数量）。16384个哈希槽全部被分配到集群节点是集群正常运行的必要条件.
• cluster_slots_ok: 哈希槽状态不是FAIL 和 PFAIL 的数量.
• cluster_slots_pfail: 哈希槽状态是 PFAIL的数量。只要哈希槽状态没有被升级到FAIL状态，这些哈希槽仍然可以被正常处理。PFAIL状态表示我们当前不能和节点进行交互，但这种状态只是临时的错误状态。
• cluster_slots_fail: 哈希槽状态是FAIL的数量。如果值不是0，那么集群节点将无法提供查询服务，除非cluster-require-full-coverage被设置为no .
• cluster_known_nodes: 集群中节点数量，包括处于握手状态还没有成为集群正式成员的节点.
• cluster_size: 至少包含一个哈希槽且能够提供服务的master节点数量.
• cluster_current_epoch: 集群本地Current Epoch变量的值。这个值在节点故障转移过程时有用，它总是递增和唯一的。
• cluster_my_epoch: 当前正在使用的节点的Config Epoch值. 这个是关联在本节点的版本值.
• cluster_stats_messages_sent: 通过node-to-node二进制总线发送的消息数量.
• cluster_stats_messages_received: 通过node-to-node二进制总线接收的消息数量.

2、cluster nodes：提供了当前连接节点所属集群的配置信息，信息格式和Redis集群在磁盘上存储使用的序列化格式完全一样（在磁盘存储信息的结尾还存储了一些额外信息）

127.0.0.1:6381> cluster nodes
b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385@16385 slave 8dbe8b347410cf87d62933382b73693405535ba1 0 1651152474000 3 connected
8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381@16381 myself,master - 0 1651152472000 1 connected 0-5460
8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383@16383 master - 0 1651152474000 3 connected 10923-16383
c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384@16384 slave 60fa7e084483feca3af41f269de5a57b526c0ad7 0 1651152476585 2 connected
60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382@16382 master - 0 1651152475573 2 connected 5461-10922
4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386@16386 slave 8335b5349d781c11745ee129f5dbae370dbd3394 0 1651152474566 1 connected
127.0.0.1:6381> 

主从关系图：

每行的组成：

<id> <ip:port> <flags> <master> <ping-sent> <pong-recv> <config-epoch> <link-state> <slot> <slot> ... <slot>

1. id: 节点ID,是一个40字节的随机字符串，这个值在节点启动的时候创建，并且永远不会改变（除非使用CLUSTER RESET HARD命令）。
2. ip:port: 客户端与节点通信使用的地址.

3. flags: 逗号分割的标记位，可能的值有: myself, master, slave, fail?, fail, handshake, noaddr, noflags. 下一部分将详细介绍这些标记.

   • myself: 当前连接的节点.
   • master: 节点是master.
   • slave: 节点是slave.
   • fail?: 节点处于PFAIL 状态。 当前节点无法联系，但逻辑上是可达的 (非 FAIL 状态).
   • fail: 节点处于FAIL 状态. 大部分节点都无法与其取得联系将会将改节点由 PFAIL 状态升级至FAIL状态。
   • handshake: 还未取得信任的节点，当前正在与其进行握手.
   • noaddr: 没有地址的节点（No address known for this node）.
   • noflags: 连个标记都没有（No flags at all）.
4. master: 如果节点是slave，并且已知master节点，则这里列出master节点ID,否则的话这里列出”-“。
5. ping-sent: 最近一次发送ping的时间，这个时间是一个unix毫秒时间戳，0代表没有发送过.
6. pong-recv: 最近一次收到pong的时间，使用unix时间戳表示.
7. config-epoch: 节点的epoch值（or of the current master if the node is a slave）。每当节点发生失败切换时，都会创建一个新的，独特的，递增的epoch。如果多个节点竞争同一个哈希槽时，epoch值更高的节点会抢夺到。
8. link-state: node-to-node集群总线使用的链接的状态，我们使用这个链接与集群中其他节点进行通信.值可以是 connected 和 disconnected.
9. slot: 哈希槽值或者一个哈希槽范围. 从第9个参数开始，后面最多可能有16384个 数(limit never reached)。代表当前节点可以提供服务的所有哈希槽值。如果只是一个值,那就是只有一个槽会被使用。如果是一个范围，这个值表示为起始槽-结束槽，节点将处理包括起始槽和结束槽在内的所有哈希槽。

官方地址：http://www.redis.cn/commands/...

3、主从容错切换迁移案例

1、数据读写存储

1、启动6机构成的集群并通过exec进入

root@docker:/data# redis-cli -p 6381
127.0.0.1:6381> set k1 v1
(error) MOVED 12706 192.168.130.132:6383
127.0.0.1:6381> set k2 v2\
OK
127.0.0.1:6381> set k3 v3
OK
127.0.0.1:6381> set k4 v4
(error) MOVED 8455 192.168.130.132:6382
127.0.0.1:6381> 

显示k1和k4没有存储进去

(error) MOVED 12706 192.168.130.132:6383：请转到6383的redis进行存储

2、防止路由失效加参数-c并新增两个key

root@docker:/data# redis-cli -p 6381 -c
127.0.0.1:6381> set k1 v1
-> Redirected to slot [12706] located at 192.168.130.132:6383
OK
192.168.130.132:6383> set k4 v4
-> Redirected to slot [8455] located at 192.168.130.132:6382
OK
192.168.130.132:6382> get k4
"v4"
192.168.130.132:6382> 

Redirected to slot [8455] located at 192.168.130.132:6382：重定向到6382

3、查看集群状态

redis-cli --cluster check 192.168.130.132:6381

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 2 keys | 5461 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 5461 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 5462 slots | 1 slaves.
[OK] 4 keys in 3 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[0-5460] (5461 slots) master
   1 additional replica(s)
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[10923-16383] (5461 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[5461-10922] (5462 slots) master
   1 additional replica(s)
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 

2、容错切换迁移

1、主6381和从机切换，先停止主机6381

[root@docker ~]# docker stop redis-node-1
redis-node-1
[root@docker ~]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED        STATUS        PORTS     NAMES
d6fc3ef2855b   redis     "docker-entrypoint.s…"   47 hours ago   Up 47 hours             redis-node-6
9c8868d69a50   redis     "docker-entrypoint.s…"   47 hours ago   Up 47 hours             redis-node-5
7fbb5345951a   redis     "docker-entrypoint.s…"   47 hours ago   Up 47 hours             redis-node-4
d53b9d5af1ac   redis     "docker-entrypoint.s…"   47 hours ago   Up 47 hours             redis-node-3
fe0e430cb940   redis     "docker-entrypoint.s…"   47 hours ago   Up 47 hours             redis-node-2
[root@docker ~]# 

6381主机停了，对应的真实从机上位，也就是6号机变成了主机器

2、查看集群情况

127.0.0.1:6382> cluster nodes
4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386@16386 master - 0 1651158299456 7 connected 0-5460
c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384@16384 slave 60fa7e084483feca3af41f269de5a57b526c0ad7 0 1651158300472 2 connected
60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382@16382 myself,master - 0 1651158298000 2 connected 5461-10922
8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383@16383 master - 0 1651158298444 3 connected 10923-16383
8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381@16381 master,fail - 1651154146064 1651154140969 1 disconnected
b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385@16385 slave 8dbe8b347410cf87d62933382b73693405535ba1 0 1651158297000 3 connected
127.0.0.1:6382> 

3、恢复3主3从

重新启动1号机之后，6号机还是主机，1号机器从之前的主机变成了从机

docker start redis-node-1

停掉6号机，再启动6号机

docker stop redis-node-6
docker start redis-node-6

查看集群状态

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 2 keys | 5461 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 5462 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 5461 slots | 1 slaves.
[OK] 4 keys in 3 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[0-5460] (5461 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[5461-10922] (5462 slots) master
   1 additional replica(s)
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[10923-16383] (5461 slots) master
   1 additional replica(s)
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 

4、主从扩容案例

1、新建6387、6388两个节点+新建后启动+查看是否8节点

docker run -d --name redis-node-7 --net host --privileged=true -v /data/redis/share/redis-node-7:/data redis --cluster-enabled yes --appendonly yes --port 6387
docker run -d --name redis-node-8 --net host --privileged=true -v /data/redis/share/redis-node-8:/data redis --cluster-enabled yes --appendonly yes --port 6388

2、进入6387容器实例内部

docker exec -it redis-node-7 /bin/bash

3、将新增的6387节点(空槽号)作为master节点加入原集群

将新增的6387作为master节点加入集群
redis-cli --cluster add-node 自己实际IP地址:6387 自己实际IP地址:6381
6387 就是将要作为master新增节点
6381 就是原来集群节点里面的领路人，相当于6387拜拜6381的码头从而找到组织加入集群

redis-cli --cluster add-node 192.168.130.132:6387 192.168.130.132:6381

root@docker:/data# redis-cli --cluster add-node 192.168.130.132:6387 192.168.130.132:6381
>>> Adding node 192.168.130.132:6387 to cluster 192.168.130.132:6381
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[0-5460] (5461 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[5461-10922] (5462 slots) master
   1 additional replica(s)
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[10923-16383] (5461 slots) master
   1 additional replica(s)
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
>>> Send CLUSTER MEET to node 192.168.130.132:6387 to make it join the cluster.
[OK] New node added correctly.
root@docker:/data# 

4、检查集群情况

redis-cli --cluster check 192.168.130.132:6381

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 2 keys | 5461 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 5462 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 5461 slots | 1 slaves.
192.168.130.132:6387 (34b689b7...) -> 0 keys | 0 slots | 0 slaves.

很明显，6387没有槽号

5、重新分配槽号

重新分派槽号
命令：redis-cli --cluster reshard IP地址:端口号

redis-cli --cluster reshard 192.168.130.:6381

输入需要迁移的槽数量，此处我们输入4096。

目标节点ID，只能指定一个，因为我们需要迁移到6387中，因此下面输入6387的ID。

[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-p6Mph4vH-1662107599722)(images/1460000038771820.jpeg)]

之后输入源节点的ID，redis会从这些源节点中平均取出对应数量的槽，然后迁移到6385中。最后要输入done表示结束。

最后输入yes即可。

6、检查集群情况

redis-cli --cluster check 192.168.130.132:6381

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6387 (34b689b7...) -> 1 keys | 4096 slots | 0 slaves.
[OK] 4 keys in 4 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[1365-5460] (4096 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[6827-10922] (4096 slots) master
   1 additional replica(s)
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[12288-16383] (4096 slots) master
   1 additional replica(s)
M: 34b689b791d9945a0b761349f1bc7b64f0be876f 192.168.130.132:6387
   slots:[0-1364],[5461-6826],[10923-12287] (4096 slots) master
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 
\

M: 34b689b791d9945a0b761349f1bc7b64f0be876f 192.168.130.132:6387
   slots:[0-1364],[5461-6826],[10923-12287] (4096 slots) master

为什么6387是3个新的区间，以前的还是连续？
重新分配成本太高，所以前3家各自匀出来一部分，从6381/6382/6383三个旧节点分别匀出1364个坑位给新节点6387

7、为主节点6387分配从节点6388

命令：redis-cli --cluster add-node ip:新slave端口 ip:新master端口 --cluster-slave --cluster-master-id 新主机节点ID

redis-cli --cluster add-node 192.168.130.132:6388 192.168.130.132:6387 --cluster-slave --cluster-master-id 34b689b791d9945a0b761349f1bc7b64f0be876f

8、检查集群情况

redis-cli --cluster check 192.168.130.132:6381

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6387 (34b689b7...) -> 1 keys | 4096 slots | 1 slaves.
[OK] 4 keys in 4 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[1365-5460] (4096 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[6827-10922] (4096 slots) master
   1 additional replica(s)
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[12288-16383] (4096 slots) master
   1 additional replica(s)
S: 4b4b4a8a4d50548e954b46e921ff8085ed555c39 192.168.130.132:6388
   slots: (0 slots) slave
   replicates 34b689b791d9945a0b761349f1bc7b64f0be876f
M: 34b689b791d9945a0b761349f1bc7b64f0be876f 192.168.130.132:6387
   slots:[0-1364],[5461-6826],[10923-12287] (4096 slots) master
   1 additional replica(s)
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 

6387存在一个子机器

5、主从缩容案例

目的：6387和6388下线

1、检查集群情况1获得6388的节点ID

redis-cli --cluster check 192.168.130.132:6382

S: 4b4b4a8a4d50548e954b46e921ff8085ed555c39 192.168.130.132:6388
   slots: (0 slots) slave
   replicates 34b689b791d9945a0b761349f1bc7b64f0be876f
M: 34b689b791d9945a0b761349f1bc7b64f0be876f 192.168.130.132:6387
   slots:[0-1364],[5461-6826],[10923-12287] (4096 slots) master
   1 additional replica(s)
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 

节点ID为：4b4b4a8a4d50548e954b46e921ff8085ed555c39

2、从集群中将节点6388删除

命令：redis-cli --cluster del-node ip:从机端口 从机6388节点ID

redis-cli --cluster del-node 192.168.130.132:6388 4b4b4a8a4d50548e954b46e921ff8085ed555c39

oot@docker:/data# redis-cli --cluster del-node 192.168.130.132:6388 4b4b4a8a4d50548e954b46e921ff8085ed555c39
>>> Removing node 4b4b4a8a4d50548e954b46e921ff8085ed555c39 from cluster 192.168.130.132:6388
>>> Sending CLUSTER FORGET messages to the cluster...
>>> Sending CLUSTER RESET SOFT to the deleted node.
root@docker:/data# 

检查集群情况

redis-cli --cluster check 192.168.130.132:6381

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6387 (34b689b7...) -> 1 keys | 4096 slots | 0 slaves.
[OK] 4 keys in 4 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[1365-5460] (4096 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[6827-10922] (4096 slots) master
   1 additional replica(s)
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[12288-16383] (4096 slots) master
   1 additional replica(s)
M: 34b689b791d9945a0b761349f1bc7b64f0be876f 192.168.130.132:6387
   slots:[0-1364],[5461-6826],[10923-12287] (4096 slots) master
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 

很明显，6387的从机器已经被没了，6388机器也已经被删除了，只剩下7台机器了。

3、将6387的槽号清空，重新分配，本例将清出来的槽号都给6381

redis-cli --cluster reshard 192.168.130.132:6381

这里我没有截到图，以阳哥的截图步骤

4、查看集群状态

redis-cli --cluster check 192.168.130.132:6381

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 2 keys | 8192 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6387 (34b689b7...) -> 0 keys | 0 slots | 0 slaves.
[OK] 4 keys in 4 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[0-6826],[10923-12287] (8192 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[6827-10922] (4096 slots) master
   1 additional replica(s)
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[12288-16383] (4096 slots) master
   1 additional replica(s)
M: 34b689b791d9945a0b761349f1bc7b64f0be876f 192.168.130.132:6387
   slots: (0 slots) master
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

6381拥有8192个槽位

5、将6387删除

命令：redis-cli --cluster del-node ip:端口 6387节点ID

redis-cli --cluster del-node 192.168.130.132:6387 34b689b791d9945a0b761349f1bc7b64f0be876f

再次检查集群情况

redis-cli --cluster check 192.168.130.132:6381

root@docker:/data# redis-cli --cluster check 192.168.130.132:6381
192.168.130.132:6381 (8335b534...) -> 2 keys | 8192 slots | 1 slaves.
192.168.130.132:6382 (60fa7e08...) -> 1 keys | 4096 slots | 1 slaves.
192.168.130.132:6383 (8dbe8b34...) -> 1 keys | 4096 slots | 1 slaves.
[OK] 4 keys in 3 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.130.132:6381)
M: 8335b5349d781c11745ee129f5dbae370dbd3394 192.168.130.132:6381
   slots:[0-6826],[10923-12287] (8192 slots) master
   1 additional replica(s)
S: c366905ca5ec2472275bbea9b2ae9b642b92a737 192.168.130.132:6384
   slots: (0 slots) slave
   replicates 60fa7e084483feca3af41f269de5a57b526c0ad7
S: 4051766aa375f0ed4533cb729afa8daf8649f5d2 192.168.130.132:6386
   slots: (0 slots) slave
   replicates 8335b5349d781c11745ee129f5dbae370dbd3394
M: 60fa7e084483feca3af41f269de5a57b526c0ad7 192.168.130.132:6382
   slots:[6827-10922] (4096 slots) master
   1 additional replica(s)
M: 8dbe8b347410cf87d62933382b73693405535ba1 192.168.130.132:6383
   slots:[12288-16383] (4096 slots) master
   1 additional replica(s)
S: b5fd469dd1f8b5a64cacd5ecaed9dd396e1b9217 192.168.130.132:6385
   slots: (0 slots) slave
   replicates 8dbe8b347410cf87d62933382b73693405535ba1
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
root@docker:/data# 

发现已经删除了