Redis Cluster--安装配置

Posted 2020-12-26

背景

本篇主要讲Redis Cluster的安装，让我们先用起来，感受一下到底是怎么回事，后面再继续学习有关如何Cluster如何failover,添加节点，删除节点，迁移slots等功能。

Redis Cluster特点

(1)Redis Cluster 共有16384(0-16383)个hash slots,数据写入时，根据CRC16('key')%16384 hash slots分配到不同的节点上；

(2)当整个集群部分节点crash不影响继续使用，如有A,B,C三个master和A1,B1,C1三个slave组成的cluster,如果B宕机，则B1会自动提成为master,当B恢复之后，也会自动成为B1的slave,保证集群的高可用性；

(3)当集群负载比较高，不足以支撑现在的业务，可以添加空节点，然后rebalance slot或者reshard slot；

安装Redis Cluster

(1)环境准备

Redis版本都是3.2.9,有6个redis实例分别在6台不同的主机上运行，其中3个作为Master,另外3个分别作为它们的Slave存在，端口统一使用默认的端口6379；

Master1: sht-sgmhadoopcm-01(172.16.101.54)

Slave1: sht-sgmhadoopdn-01(172.16.101.58)

Master2: sht-sgmhadoopnn-01(172.16.101.55)

Slave2: sht-sgmhadoopdn-02(172.16.101.59)

Master3: sht-sgmhadoopnn-02(172.16.101.56)

Slave3: sht-sgmhadoopdn-03(172.16.101.60)

#修改配置文件，每个节点都需要执行，修改其他节点对应的IP地址

[[email protected] redis]# vim redis.conf

port 6379

bind 172.16.101.54  

appendonly yes

cluster-enabled yes

cluster-config-file nodes-6379.conf

cluster-node-timeout 15000

(2)在需要ruby的节点上安装ruby

[[email protected] redis]# yum install ruby -y

#下面这一步可能报错，因为CentOS7.3默认安装的ruby2.0.0，版本太低

[[email protected] redis]# gem install redis

Fetching: redis-4.0.1.gem (100%)

Successfully installed redis-4.0.1

Parsing documentation for redis-4.0.1

Installing ri documentation for redis-4.0.1

Done installing documentation for redis after 2 seconds

1 gem installed

(3)启动所有节点

[[email protected] redis]# src/redis-server redis.conf

[[email protected] redis]# src/redis-server redis.conf

[[email protected] redis]# src/redis-server redis.conf

[[email protected] redis]# src/redis-server redis.conf

[[email protected] redis]# src/redis-server redis.conf

[[email protected] redis]# src/redis-server redis.conf

[[email protected] redis]# ps -ef|grep redis

root      1716     1  0 12:40 ?        00:00:00 src/redis-server 172.16.101.56:6379 [cluster]

root      1720  1504  0 12:41 pts/2    00:00:00 grep --color=auto redis

(4)使用redis-trib.rb脚本创建cluster

Create的过程中已经给三个master分配好了hash slots,并且制定好Slave;

选项--replicas 1 表示为每个创建的主服务器节点创建一个从服务器节点;

[[email protected] redis]# ruby src/redis-trib.rb create --replicas 1 172.16.101.54:6379 172.16.101.55:6379 172.16.101.56:6379 172.16.101.58:6379 172.16.101.59:6379 172.16.101.60:6379

>>> Creating cluster

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

Using 3 masters:

172.16.101.54:6379

172.16.101.55:6379

172.16.101.56:6379

Adding replica 172.16.101.58:6379 to 172.16.101.54:6379

Adding replica 172.16.101.59:6379 to 172.16.101.55:6379

Adding replica 172.16.101.60:6379 to 172.16.101.56:6379

M: 610aa83831404be545b25cc7f7322e987da1dd33 172.16.101.54:6379

   slots:0-5460 (5461 slots) master

M: 4c7348ac575a1a3bd4357e937a8f94f1654193cf 172.16.101.55:6379

   slots:5461-10922 (5462 slots) master

M: ece3a80f6989fa7f8316d73ee30ceea84340f24e 172.16.101.56:6379

   slots:10923-16383 (5461 slots) master

S: 28e8d5c8fd12533622d8110f8d262cb50120ca02 172.16.101.58:6379

   replicates 610aa83831404be545b25cc7f7322e987da1dd33

S: b50ba506525ee547823b3d9a7e5a095933e3ff42 172.16.101.59:6379

   replicates 4c7348ac575a1a3bd4357e937a8f94f1654193cf

S: c79de1092011ed395ee772969274c0567c2b5dd1 172.16.101.60:6379

   replicates ece3a80f6989fa7f8316d73ee30ceea84340f24e

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 172.16.101.54:6379)

M: 610aa83831404be545b25cc7f7322e987da1dd33 172.16.101.54:6379

   slots:0-5460 (5461 slots) master

   1 additional replica(s)

S: b50ba506525ee547823b3d9a7e5a095933e3ff42 172.16.101.59:6379

   slots: (0 slots) slave

   replicates 4c7348ac575a1a3bd4357e937a8f94f1654193cf

S: 28e8d5c8fd12533622d8110f8d262cb50120ca02 172.16.101.58:6379

   slots: (0 slots) slave

   replicates 610aa83831404be545b25cc7f7322e987da1dd33

M: 4c7348ac575a1a3bd4357e937a8f94f1654193cf 172.16.101.55:6379

   slots:5461-10922 (5462 slots) master

   1 additional replica(s)

M: ece3a80f6989fa7f8316d73ee30ceea84340f24e 172.16.101.56:6379

   slots:10923-16383 (5461 slots) master

   1 additional replica(s)

S: c79de1092011ed395ee772969274c0567c2b5dd1 172.16.101.60:6379

   slots: (0 slots) slave

   replicates ece3a80f6989fa7f8316d73ee30ceea84340f24e

[OK] All nodes agree about slots configuration.

>>> Check for open slots...

>>> Check slots coverage...

[OK] All 16384 slots covered.

(5)查看Cluster基本信息

[[email protected] redis]# src/redis-cli -c -h 172.16.101.54 -p 6379

172.16.101.54:6379> info replication

# Replication

role:master

connected_slaves:1

slave0:ip=172.16.101.58,port=6379,state=online,offset=2591,lag=0

master_repl_offset:2591

repl_backlog_active:1

repl_backlog_size:1048576

repl_backlog_first_byte_offset:2

repl_backlog_histlen:2590

172.16.101.54:6379> 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:4462

cluster_stats_messages_received:4462

172.16.101.54:6379> cluster nodes

b50ba506525ee547823b3d9a7e5a095933e3ff42 172.16.101.59:6379 slave 4c7348ac575a1a3bd4357e937a8f94f1654193cf 0 1532497136876 5 connected

610aa83831404be545b25cc7f7322e987da1dd33 172.16.101.54:6379 myself,master - 0 0 1 connected 0-5460

28e8d5c8fd12533622d8110f8d262cb50120ca02 172.16.101.58:6379 slave 610aa83831404be545b25cc7f7322e987da1dd33 0 1532497135872 4 connected

4c7348ac575a1a3bd4357e937a8f94f1654193cf 172.16.101.55:6379 master - 0 1532497133867 2 connected 5461-10922

ece3a80f6989fa7f8316d73ee30ceea84340f24e 172.16.101.56:6379 master - 0 1532497134870 3 connected 10923-16383

c79de1092011ed395ee772969274c0567c2b5dd1 172.16.101.60:6379 slave ece3a80f6989fa7f8316d73ee30ceea84340f24e 0 1532497137878 6 connected

[[email protected] redis]# cat nodes-6379.conf

b50ba506525ee547823b3d9a7e5a095933e3ff42 172.16.101.59:6379 slave 4c7348ac575a1a3bd4357e937a8f94f1654193cf 0 1532493960094 5 connected

610aa83831404be545b25cc7f7322e987da1dd33 172.16.101.54:6379 myself,master - 0 0 1 connected 0-5460

28e8d5c8fd12533622d8110f8d262cb50120ca02 172.16.101.58:6379 slave 610aa83831404be545b25cc7f7322e987da1dd33 0 1532493955077 4 connected

4c7348ac575a1a3bd4357e937a8f94f1654193cf 172.16.101.55:6379 master - 0 1532493958087 2 connected 5461-10922

ece3a80f6989fa7f8316d73ee30ceea84340f24e 172.16.101.56:6379 master - 0 1532493956080 3 connected 10923-16383

c79de1092011ed395ee772969274c0567c2b5dd1 172.16.101.60:6379 slave ece3a80f6989fa7f8316d73ee30ceea84340f24e 0 1532493959091 6 connected

vars currentEpoch 6 lastVoteEpoch 0

FAQ

Error1: ruby2.0.0版本太低

[[email protected] redis]# gem install redis

Fetching: redis-4.0.1.gem (100%)

ERROR:  Error installing redis:

    redis requires Ruby version >= 2.2.2.

解决方法：

[[email protected] redis]# ruby --version

ruby 2.0.0p648 (2015-12-16) [x86_64-linux]

[[email protected] redis]# gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB

[[email protected] redis]# curl -sSLhttps://get.rvm.io | bash -s stable

[[email protected] redis]# find / -name rvm -print

/usr/local/rvm

/usr/local/rvm/src/rvm

/usr/local/rvm/src/rvm/bin/rvm

/usr/local/rvm/src/rvm/lib/rvm

/usr/local/rvm/src/rvm/scripts/rvm

/usr/local/rvm/bin/rvm

/usr/local/rvm/lib/rvm

/usr/local/rvm/scripts/rvm

[[email protected] redis]# source /usr/local/rvm/scripts/rvm

[[email protected] redis]# rvm list known

[[email protected] redis]# rvm install 2.4.1

[[email protected] redis]# rvm use 2.4.1

Using /usr/local/rvm/gems/ruby-2.4.1

[[email protected] redis]# rvm use 2.4.1 --default

Using /usr/local/rvm/gems/ruby-2.4.1

[[email protected] redis]# rvm remove 2.3.4

ruby-2.3.4 - #already gone

Using /usr/local/rvm/gems/ruby-2.4.1

[[email protected] redis]# ruby --version

ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-linux]

Error2：添加节点数据不为空

[[email protected] redis]# src/redis-trib.rb add-node 172.16.101.66:6379 172.16.101.54:6379

......

[ERR] Node 172.16.101.66:6379 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：

(1)删除aof和rdb文件

(2)删除nodes-6379.conf配置文件

(3)执行flushdb and flushall

参考链接

https://redis.io/topics/cluster-tutorial