第二十一周--作业

1、简述redis集群的实现原理

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redis cluster 将所有的数据划分到16384个卡槽(slot)中,每个节点负责存储一部分卡槽,且槽位的信息也存储在每个服务节点中。

 

当redis cluster 的客户端来连接集群时，它也会得到一份集群的槽位配置信息并将其缓存在客户端本地。这样当客户端要查找某个 key 时，可以直接定位到目标节点。同时因为槽位的信息可能会存在客户端与服务器不一致的情况，还需要纠正机制来实现槽位信息的校验调整。

　　

2、基于redis5的redis cluster部署

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#创建 redis cluster集群的环境准备

每个redis 节点采用相同的redis版本、相同的密码、硬件配置

所有redis服务器必须没有任何数据

准备六台主机：

10.0.0.7   Redis-6.2.4  node1 

10.0.0.17  Redis-6.2.4  node2

10.0.0.27  Redis-6.2.4  node3

10.0.0.37  Redis-6.2.4  node4

10.0.0.47  Redis-6.2.4  node5

10.0.0.57  Redis-6.2.4  node6

 

 

#启用 redis cluster 配置

sed -i.bak -e '/masterauth/a masterauth 123456' -e '/# cluster-enabled yes/a cluster-enabled yes' -e '/# cluster-config-file nodes-6379.conf/a cluster-config-file nodes-6379.conf' -e '/cluster-require-full-coverage yes/ccluster-require-full-coverage no' /apps/redis/etc/redis.conf

 

systemctl daemon-reload

systemctl restart redis.service

 

#创建集群

redis-cli -a 123456 --cluster create 10.0.0.7:6379 10.0.0.17:6379 10.0.0.27:6379 10.0.0.37:6379 10.0.0.47:6379 10.0.0.57:6379 --cluster-replicas 1

Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.

>>> Performing hash slots allocation on 6 nodes...

Master[0] -> Slots 0 - 5460

Master[1] -> Slots 5461 - 10922

Master[2] -> Slots 10923 - 16383

Adding replica 10.0.0.47:6379 to 10.0.0.7:6379

Adding replica 10.0.0.57:6379 to 10.0.0.17:6379

Adding replica 10.0.0.37:6379 to 10.0.0.27:6379

M: 494700d188e9462f1199b97929b58338c97d1986 10.0.0.7:6379  #带M的为master

   slots:[0-5460] (5461 slots) master                      #当前master的槽位起始和结束位

M: 4ac01ebc72ebfed8e9bca715866553f9b2d48712 10.0.0.17:6379

   slots:[5461-10922] (5462 slots) master

M: c60ce314b919dcaf4c21d147f3bd808295ac9219 10.0.0.27:6379

   slots:[10923-16383] (5461 slots) master

S: b3d69d2214f157d435de6afbc5ddc0115624e658 10.0.0.37:6379  #带S的slave

   replicates c60ce314b919dcaf4c21d147f3bd808295ac9219

S: 6f3bd4e7b531e977a40f1f40820df9f85cb2e6c0 10.0.0.47:6379

   replicates 494700d188e9462f1199b97929b58338c97d1986

S: d0e5a0a4b49a804ad50583759c080afb42634ea9 10.0.0.57:6379

   replicates 4ac01ebc72ebfed8e9bca715866553f9b2d48712

Can I set the above configuration? (type 'yes' to accept): yes  #输入yes自动创建集群

>>> 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

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>>> Performing Cluster Check (using node 10.0.0.7:6379)

M: 494700d188e9462f1199b97929b58338c97d1986 10.0.0.7:6379

   slots:[0-5460] (5461 slots) master  #已经分配的槽位

   1 additional replica(s)             #分配了一个slave

S: d0e5a0a4b49a804ad50583759c080afb42634ea9 10.0.0.57:6379

   slots: (0 slots) slave              #slave没有分配槽位

   replicates 4ac01ebc72ebfed8e9bca715866553f9b2d48712  #对应的master的10.0.0.17的ID

S: 6f3bd4e7b531e977a40f1f40820df9f85cb2e6c0 10.0.0.47:6379

   slots: (0 slots) slave

   replicates 494700d188e9462f1199b97929b58338c97d1986  #对应的master的10.0.0.7的ID

S: b3d69d2214f157d435de6afbc5ddc0115624e658 10.0.0.37:6379

   slots: (0 slots) slave

   replicates c60ce314b919dcaf4c21d147f3bd808295ac9219  #对应的master的10.0.0.27的ID

M: c60ce314b919dcaf4c21d147f3bd808295ac9219 10.0.0.27:6379

   slots:[10923-16383] (5461 slots) master

   1 additional replica(s)

M: 4ac01ebc72ebfed8e9bca715866553f9b2d48712 10.0.0.17:6379

   slots:[5461-10922] (5462 slots) master

   1 additional replica(s)

[OK] All nodes agree about slots configuration.  #所有节点槽位分配完成

>>> Check for open slots...  #检查打开的槽位

>>> Check slots coverage...  #检查插槽覆盖范围

[OK] All 16384 slots covered. #所有槽位(16384个)分配完成

 

观察以上结果，可以看到3组master/slave

master:10.0.0.7---slave:10.0.0.47

master:10.0.0.17---slave:10.0.0.57

master:10.0.0.27---slave:10.0.0.37

 

#查看集群node对应关系

redis-cli -a 123456  cluster nodes

Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.

d0e5a0a4b49a804ad50583759c080afb42634ea9 10.0.0.57:6379@16379 slave 4ac01ebc72ebfed8e9bca715866553f9b2d48712 0 1652335386000 2 connected

494700d188e9462f1199b97929b58338c97d1986 10.0.0.7:6379@16379 myself,master - 0 1652335386000 1 connected 0-5460

6f3bd4e7b531e977a40f1f40820df9f85cb2e6c0 10.0.0.47:6379@16379 slave 494700d188e9462f1199b97929b58338c97d1986 0 1652335387000 1 connected

b3d69d2214f157d435de6afbc5ddc0115624e658 10.0.0.37:6379@16379 slave c60ce314b919dcaf4c21d147f3bd808295ac9219 0 1652335387608 3 connected

c60ce314b919dcaf4c21d147f3bd808295ac9219 10.0.0.27:6379@16379 master - 0 1652335386573 3 connected 10923-16383

4ac01ebc72ebfed8e9bca715866553f9b2d48712 10.0.0.17:6379@16379 master - 0 1652335388628 2 connected 5461-10922

 

#模拟master故障，对应的slave节点自动提升为新master

redis-cli -a 123456 -c INFO replication

Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.

# Replication

role:master

connected_slaves:1

slave0:ip=10.0.0.47,port=6379,state=online,offset=7770,lag=0

master_failover_state:no-failover

master_replid:2604b6e0d6c3ad7b448104bfebf3c22e1a69e5a1

master_replid2:0000000000000000000000000000000000000000

master_repl_offset:7770

second_repl_offset:-1

repl_backlog_active:1

repl_backlog_size:1048576

repl_backlog_first_byte_offset:1

repl_backlog_histlen:7770

 

#10.0.0.47自动提升为新的master

[root@node5 ~]#redis-cli -a 123456 INFO replication

Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.

# Replication

role:master

connected_slaves:0

master_failover_state:no-failover

master_replid:0b4c2c5ac6df32f3e6fff33cea5e60240da11bd2

master_replid2:2604b6e0d6c3ad7b448104bfebf3c22e1a69e5a1

master_repl_offset:8008

second_repl_offset:8009

repl_backlog_active:1

repl_backlog_size:1048576

repl_backlog_first_byte_offset:1

repl_backlog_histlen:8008

 

#恢复故障节点node1自动成为slave节点

systemctl start redis

 

#查看集群状态文件，可以查看node1自动成为slave节点

[root@node1 ~]#cat /apps/redis/data/nodes-6379.conf

b3d69d2214f157d435de6afbc5ddc0115624e658 10.0.0.37:6379@16379 slave c60ce314b919dcaf4c21d147f3bd808295ac9219 0 1652340965102 3 connected

494700d188e9462f1199b97929b58338c97d1986 10.0.0.7:6379@16379 myself,slave 6f3bd4e7b531e977a40f1f40820df9f85cb2e6c0 0 1652340965085 7 connected

6f3bd4e7b531e977a40f1f40820df9f85cb2e6c0 10.0.0.47:6379@16379 master - 0 1652340965105 7 connected 0-5460

4ac01ebc72ebfed8e9bca715866553f9b2d48712 10.0.0.17:6379@16379 master - 0 1652340965085 2 connected 5461-10922

d0e5a0a4b49a804ad50583759c080afb42634ea9 10.0.0.57:6379@16379 slave 4ac01ebc72ebfed8e9bca715866553f9b2d48712 0 1652340965085 2 connected

c60ce314b919dcaf4c21d147f3bd808295ac9219 10.0.0.27:6379@16379 master - 0 1652340965085 3 connected 10923-16383

vars currentEpoch 7 lastVoteEpoch 0