Full record of Redis cluster construction

This article summarizes basic knowledge such as the concept of redis cluster, as well as the problems and solutions encountered by individuals when building redis clusters. It is very detailed. Friends in need can refer to it

Redis Cluster is an assembly that provides data sharing among multiple Redis nodes.

Redis cluster does not support commands for processing multiple keys.

Redis cluster provides a certain degree of availability through partitioning. Commands can continue to be processed when a node is down or unavailable.

Redis cluster data sharding

In the Redis cluster, data sharding (sharding) is used instead of consistency hashing (consistency hashing) to achieve a Redis cluster Contains 16384 hash slots (hash slot). Each key in the database exists in one of these hash slots, which is determined by taking modulo 16384 after CRC16 check.

　Suppose there are three nodes in the cluster now, then

　①Node A contains hash slots 0 to 5500.

　②Node B contains hash slots 5501 to 11000.

　③Node C contains hash slots 11001 to 16384.

Then if we want to add a node, we will get a part of the slots from the three nodes ABC to D. If we remove a node, the separation slot of the removed node will be moved to the remaining slot.

Redis master-slave replication model

In order to achieve high availability of the Redis cluster. Redis provides a master-slave replication model. Each node will have N-1 replicas.

If we add a slave node to each node when creating the cluster, at this time, if one of the master nodes hangs up, its slave node will be used as the new master. Node continues to provide services. But if both the master node and the slave node hang up, they cannot continue to be used.

Redis cluster construction

Redis cluster consists of multiple cloud new Redis instances in cluster mode. The cluster mode of the instance needs to be enabled through configuration.

The following is an example of a cluster configuration file with minimal options:

port 7000
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
appendonly yes
pidfile /var/run/redis_xxxx.pid
dir /usr/local/redis-cluster/xxxx

port specifies the port number of the node

cluster- The enabled yes option is used to enable the cluster mode of the instance

cluster-config-file nodes.conf sets the path to the configuration file for saving the node. This file does not need to be modified and is created when the cluster starts.

cluster-node-timeout 5000: Sets the waiting time for method failure. That is, if the node cannot be accessed within 5 seconds, the node is considered unavailable.

appendonly yes: used to enable aof persistence

pidfile /var/run/redis_xxxx.pid sets the location of the pid file, where xxxx is the port number

dir /usr /local/redis-cluster/xxxx sets the working directory, where xxxx is the port number.

The files in the directory at this time are like this

[root@localhost 10:49 /usr/local/redis-cluster]# ll 7000 7001 7002 7003 7004 7005
7000:
总用量 7080
-rw-r--r--. 1 root root  57787 9月 10 10:44 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 09:50 redis-server

7001:
总用量 7080
-rw-r--r--. 1 root root  57787 9月 10 10:46 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7002:
总用量 7080
-rw-r--r--. 1 root root  57787 9月 10 10:46 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7003:
总用量 7080
-rw-r--r--. 1 root root  57787 9月 10 10:47 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7004:
总用量 7080
-rw-r--r--. 1 root root  57787 9月 10 10:48 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7005:
总用量 7080
-rw-r--r--. 1 root root  57787 9月 10 10:48 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server
[root@localhost 10:49 /usr/local/redis-cluster]#

Start the six nodes below

[root@localhost 10:51 /usr/local/redis-cluster]# ./7000/redis-server ./7000/redis.conf
3547:C 10 Sep 10:51:58.519 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3547:C 10 Sep 10:51:58.519 # Redis version=4.0.1, bits=32, commit=00000000, modified=0, pid=3547, just started
3547:C 10 Sep 10:51:58.519 # Configuration loaded
[root@localhost 10:51 /usr/local/redis-cluster]# ./7001/redis-server ./7001/redis.conf
3552:C 10 Sep 10:52:05.549 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3552:C 10 Sep 10:52:05.550 # Redis version=4.0.1, bits=32, commit=00000000, modified=0, pid=3552, just started
3552:C 10 Sep 10:52:05.550 # Configuration loaded
[root@localhost 10:52 /usr/local/redis-cluster]# ./7002/redis-server ./7002/redis.conf
3557:C 10 Sep 10:52:13.098 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3557:C 10 Sep 10:52:13.098 # Redis version=4.0.1, bits=32, commit=00000000, modified=0, pid=3557, just started
3557:C 10 Sep 10:52:13.098 # Configuration loaded
[root@localhost 10:52 /usr/local/redis-cluster]# ./7003/redis-server ./7003/redis.conf
3563:C 10 Sep 10:52:18.986 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3563:C 10 Sep 10:52:18.986 # Redis version=4.0.1, bits=32, commit=00000000, modified=0, pid=3563, just started
3563:C 10 Sep 10:52:18.986 # Configuration loaded
[root@localhost 10:52 /usr/local/redis-cluster]# ./7004/redis-server ./7004/redis.conf
3568:C 10 Sep 10:52:23.709 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3568:C 10 Sep 10:52:23.710 # Redis version=4.0.1, bits=32, commit=00000000, modified=0, pid=3568, just started
3568:C 10 Sep 10:52:23.710 # Configuration loaded
[root@localhost 10:52 /usr/local/redis-cluster]# ./7005/redis-server ./7005/redis.conf
3573:C 10 Sep 10:52:27.146 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3573:C 10 Sep 10:52:27.147 # Redis version=4.0.1, bits=32, commit=00000000, modified=0, pid=3573, just started
3573:C 10 Sep 10:52:27.147 # Configuration loaded
[root@localhost 10:52 /usr/local/redis-cluster]#

View the process after startup:

[root@localhost 10:52 /usr/local/redis-cluster]# ps aux|grep redis
root   3548 0.2 0.2 41964 2288 ?    Ssl 10:51  0:00 ./7000/redis-server 127.0.0.1:7000 [cluster]
root   3553 0.1 0.2 41964 2288 ?    Ssl 10:52  0:00 ./7001/redis-server 127.0.0.1:7001 [cluster]
root   3558 0.2 0.2 41964 2288 ?    Ssl 10:52  0:00 ./7002/redis-server 127.0.0.1:7002 [cluster]
root   3564 0.1 0.2 41964 2292 ?    Ssl 10:52  0:00 ./7003/redis-server 127.0.0.1:7003 [cluster]
root   3569 0.2 0.2 41964 2292 ?    Ssl 10:52  0:00 ./7004/redis-server 127.0.0.1:7004 [cluster]
root   3574 0.1 0.2 41964 2288 ?    Ssl 10:52  0:00 ./7005/redis-server 127.0.0.1:7005 [cluster]
root   3580 0.0 0.0  6048  784 pts/2  S+  10:52  0:00 grep redis
[root@localhost 10:52 /usr/local/redis-cluster]#

View the file directory again:

[root@localhost 11:01 /usr/local/redis-cluster]# ll 7000 7001 7002 7003 7004 7005
7000:
总用量 7084
-rw-r--r--. 1 root root    0 9月 10 10:51 appendonly.aof
-rw-r--r--. 1 root root   114 9月 10 10:51 nodes-7000.conf
-rw-r--r--. 1 root root  57787 9月 10 10:44 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 09:50 redis-server

7001:
总用量 7084
-rw-r--r--. 1 root root    0 9月 10 10:52 appendonly.aof
-rw-r--r--. 1 root root   114 9月 10 10:52 nodes-7001.conf
-rw-r--r--. 1 root root  57787 9月 10 10:46 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7002:
总用量 7084
-rw-r--r--. 1 root root    0 9月 10 10:52 appendonly.aof
-rw-r--r--. 1 root root   114 9月 10 10:52 nodes-7002.conf
-rw-r--r--. 1 root root  57787 9月 10 10:46 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7003:
总用量 7084
-rw-r--r--. 1 root root    0 9月 10 10:52 appendonly.aof
-rw-r--r--. 1 root root   114 9月 10 10:52 nodes-7003.conf
-rw-r--r--. 1 root root  57787 9月 10 10:47 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7004:
总用量 7084
-rw-r--r--. 1 root root    0 9月 10 10:52 appendonly.aof
-rw-r--r--. 1 root root   114 9月 10 10:52 nodes-7004.conf
-rw-r--r--. 1 root root  57787 9月 10 10:48 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server

7005:
总用量 7084
-rw-r--r--. 1 root root    0 9月 10 10:52 appendonly.aof
-rw-r--r--. 1 root root   114 9月 10 10:52 nodes-7005.conf
-rw-r--r--. 1 root root  57787 9月 10 10:48 redis.conf
-rwxr-xr-x. 1 root root 7185872 9月 10 10:04 redis-server
[root@localhost 11:01 /usr/local/redis-cluster]#

You can see the generated aof and nodes files, a dump file will be generated when saving.

Looking at the pid

[root@localhost 11:03 /usr/local/redis-cluster]# ll /var/run/redis*
-rw-r--r--. 1 root root 5 9月 10 10:51 /var/run/redis_7000.pid
-rw-r--r--. 1 root root 5 9月 10 10:52 /var/run/redis_7001.pid
-rw-r--r--. 1 root root 5 9月 10 10:52 /var/run/redis_7002.pid
-rw-r--r--. 1 root root 5 9月 10 10:52 /var/run/redis_7003.pid
-rw-r--r--. 1 root root 5 9月 10 10:52 /var/run/redis_7004.pid
-rw-r--r--. 1 root root 5 9月 10 10:52 /var/run/redis_7005.pid
[root@localhost 11:03 /usr/local/redis-cluster]#

Next, we need to use the redis-trib tool and these six nodes to create a cluster.

redis-trib is located in the src directory of the redis source code.

We copy a copy to the redis-cluster directory.

[root@localhost 11:03 /usr/local/redis-cluster]# ll ../redis/src/redis-trib*
-rwxrwxr-x. 1 root root 60843 7月 24 22:58 ../redis/src/redis-trib.rb
[root@localhost 11:04 /usr/local/redis-cluster]# cp ../redis/src/redis-trib.rb ./
[root@localhost 11:05 /usr/local/redis-cluster]# ll
总用量 84
drwxr-xr-x. 2 root root 4096 9月 10 10:51 7000
drwxr-xr-x. 2 root root 4096 9月 10 10:52 7001
drwxr-xr-x. 2 root root 4096 9月 10 10:52 7002
drwxr-xr-x. 2 root root 4096 9月 10 10:52 7003
drwxr-xr-x. 2 root root 4096 9月 10 10:52 7004
drwxr-xr-x. 2 root root 4096 9月 10 10:52 7005
-rwxr-xr-x. 1 root root 60843 9月 10 11:05 redis-trib.rb
[root@localhost 11:05 /usr/local/redis-cluster]#

Start starting the cluster:

[root@localhost 11:13 /usr/local/redis-cluster]# ./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
/usr/bin/env: ruby: 没有那个文件或目录
[root@localhost 11:15 /usr/local/redis-cluster]#

The following is my failed installation version, and there are also successful versions later.

Because it is a ruby ​​program, we need to install ruby,

yum -y install ruby

Continue to start the cluster:

[root@localhost 11:21 /usr/local/redis-cluster]# ./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
./redis-trib.rb:24:in `require': no such file to load -- rubygems (LoadError)
    from ./redis-trib.rb:24
[root@localhost 11:22 /usr/local/redis-cluster]#

Still reported an error, saying rubygems is needed, we continue to install:

yum -y install rubygems

Continue to start the cluster:

[root@localhost 11:24 /usr/local/redis-cluster]# ./redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require': no such file to load -- redis (LoadError)
    from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
    from ./redis-trib.rb:25
[root@localhost 11:24 /usr/local/redis-cluster]#

Still getting an error..., we need to install a higher version of ruby.

So, I decided to uninstall Ruby 1.8 first.

yum -y remove ruby

Then reinstall

##

wget https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.4.1.tar.gz
tar xzvf ruby-2.4.1.tar.gz
cd ruby-2.4.1
./configure
make
make install

Then check the ruby ​​version:

[root@localhost 12:47 ~]# ruby -v
ruby 2.4.1p111 (2017-03-22 revision 58053) [i686-linux]
[root@localhost 12:47 ~]#

Finally, in order to run redis-trib we need to install the redis gem.

If the following error occurs

[root@localhost 13:01 /usr/local/redis-cluster]# gem install redis
ERROR: Loading command: install (LoadError)
    cannot load such file -- zlib
ERROR: While executing gem ... (NoMethodError)
  undefined method `invoke_with_build_args' for nil:NilClass

We continue to open the cluster: the error is still reported, and after several twists and turns, it is still not resolved

Finally OK, I found the following method.

Successful version

Install ruby ​​through rvm, the ruby ​​management tool.

First install rvm. If the following command prompts that curl cannot be found, you can install crul through yum install -y crul.

[root@localhost 19:45 ~]# curl -L get.rvm.io | bash -s stable
 % Total  % Received % Xferd Average Speed  Time  Time   Time Current
                 Dload Upload  Total  Spent  Left Speed
100 24090 100 24090  0   0 11517   0 0:00:02 0:00:02 --:--:-- 48276
Downloading https://github.com/rvm/rvm/archive/1.29.3.tar.gz
Downloading https://github.com/rvm/rvm/releases/download/1.29.3/1.29.3.tar.gz.asc
gpg: 于 2017年09月11日 星期一 05时59分21秒 JST 创建的签名，使用 RSA，钥匙号 BF04FF17
gpg: 无法检查签名：No public key
Warning, RVM 1.26.0 introduces signed releases and automated check of signatures when GPG software found. Assuming you trust Michal Papis import the mpapis public key (downloading the signatures).

GPG signature verification failed for '/usr/local/rvm/archives/rvm-1.29.3.tgz' - 'https://github.com/rvm/rvm/releases/download/1.29.3/1.29.3.tar.gz.asc'! Try to install GPG v2 and then fetch the public key:

  gpg2 --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3

or if it fails:

  command curl -sSL https://rvm.io/mpapis.asc | gpg2 --import -

the key can be compared with:

  https://rvm.io/mpapis.asc
  https://keybase.io/mpapis

NOTE: GPG version 2.1.17 have a bug which cause failures during fetching keys from remote server. Please downgrade or upgrade to newer version (if available) or use the second method described above.

[root@localhost 19:45 ~]#

Found that it failed, we followed the prompts.

[root@localhost 19:45 ~]# curl -sSL https://rvm.io/mpapis.asc | gpg2 --import -
gpg: 钥匙环‘/root/.gnupg/secring.gpg'已建立
gpg: /root/.gnupg/trustdb.gpg：建立了信任度数据库
gpg: 密钥 D39DC0E3：公钥“Michal Papis (RVM signing) <mpapis@gmail.com>”已导入
gpg: 合计被处理的数量：1
gpg:      已导入：1 (RSA: 1)
gpg: 没有找到任何绝对信任的密钥
[root@localhost 19:45 ~]# curl -L get.rvm.io | bash -s stable
 % Total  % Received % Xferd Average Speed  Time  Time   Time Current
                 Dload Upload  Total  Spent  Left Speed
100 24090 100 24090  0   0  3763   0 0:00:06 0:00:06 --:--:-- 3763
Downloading https://github.com/rvm/rvm/archive/1.29.3.tar.gz
Downloading https://github.com/rvm/rvm/releases/download/1.29.3/1.29.3.tar.gz.asc
gpg: 于 2017年09月11日 星期一 05时59分21秒 JST 创建的签名，使用 RSA，钥匙号 BF04FF17
gpg: 完好的签名，来自于“Michal Papis (RVM signing) <mpapis@gmail.com>”
gpg:        亦即“Michal Papis <michal.papis@toptal.com>”
gpg:        亦即“[jpeg image of size 5015]”
gpg: 警告：这把密钥未经受信任的签名认证！
gpg:    没有证据表明这个签名属于它所声称的持有者。
主钥指纹： 409B 6B17 96C2 7546 2A17 0311 3804 BB82 D39D C0E3
子钥指纹： 62C9 E5F4 DA30 0D94 AC36 166B E206 C29F BF04 FF17
GPG verified &#39;/usr/local/rvm/archives/rvm-1.29.3.tgz&#39;
Creating group &#39;rvm&#39;

Installing RVM to /usr/local/rvm/
Installation of RVM in /usr/local/rvm/ is almost complete:

 * First you need to add all users that will be using rvm to &#39;rvm&#39; group,
  and logout - login again, anyone using rvm will be operating with `umask u=rwx,g=rwx,o=rx`.

 * To start using RVM you need to run `source /etc/profile.d/rvm.sh`
  in all your open shell windows, in rare cases you need to reopen all shell windows.
[root@localhost 19:46 ~]

It is found that rvm has been installed successfully. In order for the configuration to take effect immediately, we need to use the source command to import the rvm configuration file.

Check the path of the configuration file first, and then import it.

[root@localhost 19:46 ~]# find / -name rvm.sh
/etc/profile.d/rvm.sh
[root@localhost 19:49 ~]# source /etc/profile.d/rvm.sh

接下来就可以安装高版本的ruby了，建议安装2.2.3版本，不然的话，等下gen install redis的时候，可能会报下面的错误：

[root@localhost 19:59 ~]# gem install redis
Fetching: redis-4.0.0.gem (100%)
ERROR: Error installing redis:
    redis requires Ruby version >= 2.2.2.

废话少说，接下来安装2.2.3版本的ruby

[root@localhost 20:16 ~]# rvm install 2.3.3
Searching for binary rubies, this might take some time.
No binary rubies available for: centos/6/i386/ruby-2.3.3.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for centos.
Requirements installation successful.
Installing Ruby from source to: /usr/local/rvm/rubies/ruby-2.3.3, this may take a while depending on your cpu(s)...
ruby-2.3.3 - #downloading ruby-2.3.3, this may take a while depending on your connection...
 % Total  % Received % Xferd Average Speed  Time  Time   Time Current
                 Dload Upload  Total  Spent  Left Speed
100 13.7M 100 13.7M  0   0 1285k   0 0:00:10 0:00:10 --:--:-- 1394k
ruby-2.3.3 - #extracting ruby-2.3.3 to /usr/local/rvm/src/ruby-2.3.3....
ruby-2.3.3 - #applying patch /usr/local/rvm/patches/ruby/ruby_2_3_gcc7.patch.
ruby-2.3.3 - #applying patch /usr/local/rvm/patches/ruby/2.3.3/random_c_using_NR_prefix.patch.
ruby-2.3.3 - #configuring..........................................................
ruby-2.3.3 - #post-configuration..
ruby-2.3.3 - #compiling....................................................................................-
ruby-2.3.3 - #installing...........................
ruby-2.3.3 - #making binaries executable..
ruby-2.3.3 - #downloading rubygems-2.6.13
ruby-2.3.3 - #extracting rubygems-2.6.13.....
ruby-2.3.3 - #removing old rubygems.........
ruby-2.3.3 - #installing rubygems-2.6.13..........................
ruby-2.3.3 - #gemset created /usr/local/rvm/gems/ruby-2.3.3@global
ruby-2.3.3 - #importing gemset /usr/local/rvm/gemsets/global.gems..........................................|
ruby-2.3.3 - #generating global wrappers........
ruby-2.3.3 - #gemset created /usr/local/rvm/gems/ruby-2.3.3
ruby-2.3.3 - #importing gemsetfile /usr/local/rvm/gemsets/default.gems evaluated to empty gem list
ruby-2.3.3 - #generating default wrappers........
ruby-2.3.3 - #adjusting #shebangs for (gem irb erb ri rdoc testrb rake).
Install of ruby-2.3.3 - #complete
Please be aware that you just installed a ruby that requires 2 patches just to be compiled on an up to date linux system.
This may have known and unaccounted for security vulnerabilities.
Please consider upgrading to ruby-2.4.1 which will have all of the latest security patches.
Ruby was built without documentation, to build it run: rvm docs generate-ri
[root@localhost 20:27 ~]# ruby -v
ruby 2.3.3p222 (2016-11-21 revision 56859) [i686-linux]
[root@localhost 20:28 ~]# gem -v
2.6.13
[root@localhost 20:28 ~]#

可以看到，不进ruby安装好了2.3.3版本，还把rubygems也安装好了。

如果要删除掉某个版本的ruby可以用这个命令：rvm remove 1.9.3。

我们继续安装：

[root@localhost 20:28 ~]# gem install redis
Fetching: redis-4.0.0.gem (100%)
Successfully installed redis-4.0.0
Parsing documentation for redis-4.0.0
Installing ri documentation for redis-4.0.0
Done installing documentation for redis after 3 seconds
1 gem installed
[root@localhost 20:33 ~]#

看到这里，折腾了两个晚上终于弄好了。接下来就是使用我们的redis-trib开启集群了。

为了方便，我把redis-trib.rb这个文件复制了一份到/usr/local/bin这个目录下，因为这个目录在PATH下面，里面的命令可以直接执行。

再次确认下六个redis节点的运行是ok的。

[root@localhost 20:35 /usr/local/redis-cluster]# ps aux|grep redis
root   2486 0.1 0.2 46060 2304 ?    Ssl 18:30  0:12 ./7000/redis-server 127.0.0.1:7000 [cluster]
root   2491 0.1 0.2 46060 2308 ?    Ssl 18:30  0:13 ./7001/redis-server 127.0.0.1:7001 [cluster]
root   2496 0.1 0.2 46060 2308 ?    Ssl 18:30  0:13 ./7002/redis-server 127.0.0.1:7002 [cluster]
root   2501 0.1 0.2 46060 2304 ?    Ssl 18:30  0:13 ./7003/redis-server 127.0.0.1:7003 [cluster]
root   2506 0.1 0.2 46060 2308 ?    Ssl 18:30  0:14 ./7004/redis-server 127.0.0.1:7004 [cluster]
root   2511 0.1 0.2 46060 2304 ?    Ssl 18:30  0:12 ./7005/redis-server 127.0.0.1:7005 [cluster]
root   31426 0.0 0.0  6048  784 pts/2  S+  20:35  0:00 grep redis
[root@localhost 20:35 /usr/local/redis-cluster]#

[root@localhost 20:35 /usr/local/redis-cluster]# redis-trib.rb create --replicas 1 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
>>> Creating cluster
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
127.0.0.1:7000
127.0.0.1:7001
127.0.0.1:7002
Adding replica 127.0.0.1:7003 to 127.0.0.1:7000
Adding replica 127.0.0.1:7004 to 127.0.0.1:7001
Adding replica 127.0.0.1:7005 to 127.0.0.1:7002
M: 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2 127.0.0.1:7000
  slots:0-5460 (5461 slots) master
M: 9bf2ee5d32fc350ec411d3eaad18f82492796e99 127.0.0.1:7001
  slots:5461-10922 (5462 slots) master
M: 6de604de12b4b4a3be46766bb95ccf4618dc0d75 127.0.0.1:7002
  slots:10923-16383 (5461 slots) master
S: f1bdbd841e37825169426486d6502e2cd99b76fe 127.0.0.1:7003
  replicates 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2
S: 3ff95d180ec47fc58c9c5f73e2f54354128bfe7e 127.0.0.1:7004
  replicates 9bf2ee5d32fc350ec411d3eaad18f82492796e99
S: a4a09d80a4bb6c82345c376c59e5ae49e1d49701 127.0.0.1:7005
  replicates 6de604de12b4b4a3be46766bb95ccf4618dc0d75
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 127.0.0.1:7000)
M: 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2 127.0.0.1:7000
  slots:0-5460 (5461 slots) master
  1 additional replica(s)
S: f1bdbd841e37825169426486d6502e2cd99b76fe 127.0.0.1:7003
  slots: (0 slots) slave
  replicates 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2
M: 6de604de12b4b4a3be46766bb95ccf4618dc0d75 127.0.0.1:7002
  slots:10923-16383 (5461 slots) master
  1 additional replica(s)
M: 9bf2ee5d32fc350ec411d3eaad18f82492796e99 127.0.0.1:7001
  slots:5461-10922 (5462 slots) master
  1 additional replica(s)
S: 3ff95d180ec47fc58c9c5f73e2f54354128bfe7e 127.0.0.1:7004
  slots: (0 slots) slave
  replicates 9bf2ee5d32fc350ec411d3eaad18f82492796e99
S: a4a09d80a4bb6c82345c376c59e5ae49e1d49701 127.0.0.1:7005
  slots: (0 slots) slave
  replicates 6de604de12b4b4a3be46766bb95ccf4618dc0d75
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[root@localhost 20:37 /usr/local/redis-cluster]#

在创建的过程中，redis会给出一份预想的配置给我们看，确定没问题就输入yes并回车。系统就给我们创建了三个主，三个从的集群结构。

可以看到All 16384 slots covered。

redis-cli

redis-cli默认情况下连接的是本地的6379端口的redis服务器。

现在有六个端口，所以需要指定参数。

redis-cli -h xxx -p xxx -a xxx

-h：指定服务器

-p：指定端口号

-a：指定密码

-c：开启集群模式

[root@localhost 20:53 /usr/local/redis-cluster]# redis-cli -c -p 7000
127.0.0.1:7000> set name zhangsan
-> Redirected to slot [5798] located at 127.0.0.1:7001
OK
127.0.0.1:7001> exit
[root@localhost 20:53 /usr/local/redis-cluster]# redis-cli -c -p 7002
127.0.0.1:7002> get name
-> Redirected to slot [5798] located at 127.0.0.1:7001
"zhangsan"
127.0.0.1:7001>

可以看到，已经可以共享数据了。

 但是，如果我们把某一个主节点杀掉呢？

[root@localhost 19:52 /usr/local/redis-cluster]# redis-cli -p 7002 debug segfault
Error: Server closed the connection
[root@localhost 19:53 /usr/local/redis-cluster]# redis-trib.rb check 127.0.0.1:7000
>>> Performing Cluster Check (using node 127.0.0.1:7000)
M: 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2 127.0.0.1:7000
  slots:0-5460 (5461 slots) master
  1 additional replica(s)
M: 9bf2ee5d32fc350ec411d3eaad18f82492796e99 127.0.0.1:7001
  slots:5461-10922 (5462 slots) master
  1 additional replica(s)
S: 3ff95d180ec47fc58c9c5f73e2f54354128bfe7e 127.0.0.1:7004
  slots: (0 slots) slave
  replicates 9bf2ee5d32fc350ec411d3eaad18f82492796e99
M: a4a09d80a4bb6c82345c376c59e5ae49e1d49701 127.0.0.1:7005
  slots:10923-16383 (5461 slots) master
  0 additional replica(s)
S: f1bdbd841e37825169426486d6502e2cd99b76fe 127.0.0.1:7003
  slots: (0 slots) slave
  replicates 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[root@localhost 19:54 /usr/local/redis-cluster]#

可以看到7005端口的节点已经变成主节点了。那如果继续把7005节点也宕掉呢？

[root@localhost 19:58 /usr/local/redis-cluster]# redis-cli -p 7005 debug segfault
Error: Server closed the connection
[root@localhost 19:58 /usr/local/redis-cluster]# redis-trib.rb check 127.0.0.1:7000
[ERR] Sorry, can't connect to node 127.0.0.1:7005
>>> Performing Cluster Check (using node 127.0.0.1:7000)
M: 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2 127.0.0.1:7000
  slots:0-5460 (5461 slots) master
  1 additional replica(s)
M: 9bf2ee5d32fc350ec411d3eaad18f82492796e99 127.0.0.1:7001
  slots:5461-10922 (5462 slots) master
  1 additional replica(s)
S: 3ff95d180ec47fc58c9c5f73e2f54354128bfe7e 127.0.0.1:7004
  slots: (0 slots) slave
  replicates 9bf2ee5d32fc350ec411d3eaad18f82492796e99
S: f1bdbd841e37825169426486d6502e2cd99b76fe 127.0.0.1:7003
  slots: (0 slots) slave
  replicates 6d996f9e34f40b02afe06aa9d3c8f18a41875cb2
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[ERR] Not all 16384 slots are covered by nodes.
[root@localhost 19:58 /usr/local/redis-cluster]#

可以看到集群已经出现问题了。

追记：

在搭建多机多点集群的时候，遇到以下问题：

1、一直在等待...

>>> 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.......................

解决办法：确认端口是否开放。如果没有开发，可以修改/etc/sysconfig/iptables文件，开放端口（复制一行前面开放端口的来修改），然后service iptables restart重启防火墙。

极端的可以service iptables stop来关闭防火墙

2、槽被利用

/usr/local/rvm/gems/ruby-2.3.3/gems/redis-4.0.0/lib/redis/client.rb:119:in `call': ERR Slot 5461 is already busy (Redis::CommandError)
 from /usr/local/rvm/gems/ruby-2.3.3/gems/redis-4.0.0/lib/redis.rb:2742:in `block in method_missing'
 from /usr/local/rvm/gems/ruby-2.3.3/gems/redis-4.0.0/lib/redis.rb:45:in `block in synchronize'
 from /usr/local/rvm/rubies/ruby-2.3.3/lib/ruby/2.3.0/monitor.rb:214:in `mon_synchronize'
 from /usr/local/rvm/gems/ruby-2.3.3/gems/redis-4.0.0/lib/redis.rb:45:in `synchronize'
 from /usr/local/rvm/gems/ruby-2.3.3/gems/redis-4.0.0/lib/redis.rb:2741:in `method_missing'
 from /usr/local/bin/redis-trib.rb:212:in `flush_node_config'
 from /usr/local/bin/redis-trib.rb:776:in `block in flush_nodes_config'
 from /usr/local/bin/redis-trib.rb:775:in `each'
 from /usr/local/bin/redis-trib.rb:775:in `flush_nodes_config'
 from /usr/local/bin/redis-trib.rb:1296:in `create_cluster_cmd'
 from /usr/local/bin/redis-trib.rb:1700:in `<main>&#39;

解决办法：删除掉在redis.conf的dir目录下的几个文件redis.conf文件除外。

如果还是有相同的问题，可以考虑对所有节点执行下面两个命令。

redis-cli -p 端口号-h 主机物理地址 FLUSHALL

redis-cli -p 端口号-h 主机物理地址 CLUSTER RESET SOFT

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