Redis Cluster Setup and simple to use
Describes the installation environment and version
With two virtual machines simulate six nodes, a machine three nodes, create 3 master, 3 salve environment.
using redis redis-3.2.4 version.
Two virtual machines are CentOS, a CentOS6.5 (IP: 192.168.31.245), a CentOS7 (IP: 192.168.31.210).
Installation process
1. Download and unzip
cd
/root/software
wget http:
//download
.redis.io
/releases/redis-3
.2.4.
tar
.gz
tar
-zxvf redis-3.2.4.
tar
.gz
2. compile and install
cd redis-3.2.4 make && make install
3. Copy redis-trib.rb to the / usr / local / bin directory
cd src cp redis-trib.rb /usr/local/bin/
4. Create Redis nodes
First, create a directory under redis_cluster 192.168.31.245 on the machine /root/software/redis-3.2.4 directory;
mkdir redis_cluster
In redis_cluster directory, create a directory called 7000,7001,7002, and redis.conf copied to the three directories
mkdir 7000 7001 7002<br>cp redis.conf redis_cluster/7000 cp redis.conf redis_cluster/7001 cp redis.conf redis_cluster/7002
Three profiles are modified, the following modifications
port 7000 // port 7000,7002,7003 the bind native ip // ip default ip to 127.0.0.1 need to switch to another node machine accessible or can not access the corresponding port when you create a cluster, you can not create a cluster daemonize yes // redis background pidfile /var/run/redis_7000.pid // pidfile file corresponds 7000,7001,7002 cluster-Enabled yes // Enable the cluster to comment # remove cluster-config-file nodes_7000.conf // cluster configuration profiles first start automatically generating 7000,7001,7002 Cluster-Node-request timeout timeout 15000 // default 15 seconds, may be provided on their own appendonly yes // aof log need to turn on, each time it writes a log is recorded
- Then on another machine (192.168.31.210), the above operation is repeated three steps, but the directory to 7003,7004,7005, modify the corresponding profile in accordance with this rule to
5. Start each node
Performed on a first machine Redis redis_cluster-Server / 7000 / redis.conf Redis redis_cluster-Server / 7001 / redis.conf Redis redis_cluster-Server / 7002 / redis.conf performed on another machine redis-server redis_cluster / 7003 / redis .conf Redis redis_cluster-Server / 7004 / redis.conf Redis redis_cluster-Server / 7005 / redis.conf
6. Check redis start case
##一台机器<br>ps -ef | grep redis
root 61020 1 0 02:14 ? 00:00:01 redis-server 127.0.0.1:7000 [cluster]
root 61024 1 0 02:14 ? 00:00:01 redis-server 127.0.0.1:7001 [cluster]
root 61029 1 0 02:14 ? 00:00:01 redis-server 127.0.0.1:7002 [cluster]
netstat -tnlp | grep redis
tcp 0 0 127.0.0.1:17000 0.0.0.0:* LISTEN 61020/redis-server
tcp 0 0 127.0.0.1:17001 0.0.0.0:* LISTEN 61024/redis-server
tcp 0 0 127.0.0.1:17002 0.0.0.0:* LISTEN 61029/redis-server
0 0 127.0.0.1:7000 0.0.0.0:* the LISTEN TCP 61020 / Redis-Server
? root 9964 1 0 02:32 00:00:01 Redis-Server 127.0.0.1:7004 [Cluster]
0 0 127.0.0.1:7001 0.0.0.0:* the LISTEN TCP 61024 / Redis-Server
TCP 61029 0 0 127.0.0.1:7002 0.0.0.0:* the LISTEN / Redis-Server
. 1
2
. 3
. 4
. 5
. 6
. 7
. 8
. 9
10
. 11
12 is
13
## another machine
PS -ef | grep Redis
root 9957 1 0 02:32 00:00:01 Redis-Server 127.0.0.1:7003 [Cluster]?
root 9971 1 0 02:32 00:00:01? Server-127.0.0.1:7005 Redis [Cluster]
the root PTS 02:38 10065 4744 of 0/0 = Auto Redis 00:00:00 grep --color
the netstat -tlnp | grep Redis
tcp 0 0 127.0.0.1:17003 0.0.0.0:* LISTEN 9957/redis-server 1
tcp 0 0 127.0.0.1:17004 0.0.0.0:* LISTEN 9964/redis-server 1
tcp 0 0 127.0.0.1:17005 0.0.0.0:* LISTEN 9971/redis-server 1
tcp 0 0 127.0.0.1:7003 0.0.0.0:* LISTEN 9957/redis-server 1
tcp 0 0 127.0.0.1:7004 0.0.0.0:* LISTEN 9964/redis-server 1
tcp 0 0 127.0.0.1:7005 0.0.0.0:* LISTEN 9971/redis-server 1
7. Create a cluster
Redis official offers redis-trib.rb this tool, in the src directory unpacked directory, the third step it has been copied to / usr / local / bin directory, can be used directly on the command line. Use the following command to complete the installation.
redis-trib.rb create --replicas 1 192.168.31.245:7000 192.168.31.245:7001 192.168.31.245:7002 192.168.31.210:7003 192.168.31.210:7004 192.168.31.210:7005
Wherein, the first three ip: port node is the first machine, the second machine to the remaining three.
And so wrong. This tool is used ruby achieve, so you need to install ruby. Installation command as follows:
yum -y
install
ruby ruby-devel rubygems rpm-build
gem install redis
After the run redis-trib.rb command, states the following:
Enter yes to, then the following appears, the installation was successful.
8. Cluster Verification
The cluster nodes connected to the port 7002 on the first machine, in another 7005 node connected to a connection mode is redis-cli -h192.168.31.245 -c -p 7002, additional parameters may be connected to the cluster -C, because the above redis.conf bind to the ip address, so -h parameter can not be omitted.
In Run 7005 node set hello world, performed as follows:
Then another one 7002 port, view the key to hello content, GET hello, execution results are as follows:
Description Cluster work properly.
Briefly about principle
redis cluster in the design, to take into account to the center, to the middleware, that is, each node in the cluster are equal relationship are peers, each node keeps their data and entire the state of the cluster. Each node and all other nodes are connected, and these connections remain active, thus ensuring that we only need to connect any node in the cluster, you can get the data to other nodes.
Redis 集群没有并使用传统的一致性哈希来分配数据，而是采用另外一种叫做哈希槽 (hash slot)的方式来分配的。redis cluster 默认分配了 16384 个slot，当我们set一个key 时，会用CRC16算法来取模得到所属的slot，然后将这个key 分到哈希槽区间的节点上，具体算法就是：CRC16(key) % 16384。所以我们在测试的时候看到set 和 get 的时候，直接跳转到了7000端口的节点。
Redis 集群会把数据存在一个 master 节点，然后在这个 master 和其对应的salve 之间进行数据同步。当读取数据时，也根据一致性哈希算法到对应的 master 节点获取数据。只有当一个master 挂掉之后，才会启动一个对应的 salve 节点，充当 master 。
需要注意的是：必须要3个或以上的主节点，否则在创建集群时会失败，并且当存活的主节点数小于总节点数的一半时，整个集群就无法提供服务了。
介绍安装环境与版本
用两台虚拟机模拟6个节点，一台机器3个节点，创建出3 master、3 salve 环境。
redis 采用 redis-3.2.4 版本。
两台虚拟机都是 CentOS ，一台 CentOS6.5 （IP:192.168.31.245），一台 CentOS7（IP:192.168.31.210） 。
安装过程
1. 下载并解压
cd
/root/software
wget http:
//download
.redis.io
/releases/redis-3
.2.4.
tar
.gz
tar
-zxvf redis-3.2.4.
tar
.gz
2. 编译安装
cd redis-3.2.4 make && make install
3. 将 redis-trib.rb 复制到 /usr/local/bin 目录下
cd src cp redis-trib.rb /usr/local/bin/
4. 创建 Redis 节点
首先在 192.168.31.245 机器上 /root/software/redis-3.2.4 目录下创建 redis_cluster 目录；
mkdir redis_cluster
在 redis_cluster 目录下，创建名为7000、7001、7002的目录，并将 redis.conf 拷贝到这三个目录中
mkdir 7000 7001 7002<br>cp redis.conf redis_cluster/7000 cp redis.conf redis_cluster/7001 cp redis.conf redis_cluster/7002
分别修改这三个配置文件，修改如下内容
port 7000 //端口7000,7002,7003 bind 本机ip //默认ip为127.0.0.1 需要改为其他节点机器可访问的ip 否则创建集群时无法访问对应的端口，无法创建集群 daemonize yes //redis后台运行 pidfile /var/run/redis_7000.pid //pidfile文件对应7000,7001,7002 cluster-enabled yes //开启集群 把注释#去掉 cluster-config-file nodes_7000.conf //集群的配置 配置文件首次启动自动生成 7000,7001,7002 cluster-node-timeout 15000 //请求超时 默认15秒，可自行设置 appendonly yes //aof日志开启 有需要就开启，它会每次写操作都记录一条日志
- 接着在另外一台机器上（192.168.31.210），的操作重复以上三步，只是把目录改为7003、7004、7005，对应的配置文件也按照这个规则修改即可
5. 启动各个节点
第一台机器上执行 redis-server redis_cluster/7000/redis.conf redis-server redis_cluster/7001/redis.conf redis-server redis_cluster/7002/redis.conf 另外一台机器上执行 redis-server redis_cluster/7003/redis.conf redis-server redis_cluster/7004/redis.conf redis-server redis_cluster/7005/redis.conf
6. 检查 redis 启动情况
##一台机器<br>ps -ef | grep redis
root 61020 1 0 02:14 ? 00:00:01 redis-server 127.0.0.1:7000 [cluster]
root 61024 1 0 02:14 ? 00:00:01 redis-server 127.0.0.1:7001 [cluster]
root 61029 1 0 02:14 ? 00:00:01 redis-server 127.0.0.1:7002 [cluster]
netstat -tnlp | grep redis
tcp 0 0 127.0.0.1:17000 0.0.0.0:* LISTEN 61020/redis-server
tcp 0 0 127.0.0.1:17001 0.0.0.0:* LISTEN 61024/redis-server
tcp 0 0 127.0.0.1:17002 0.0.0.0:* LISTEN 61029/redis-server
tcp 0 0 127.0.0.1:7000 0.0.0.0:* LISTEN 61020/redis-server
tcp 0 0 127.0.0.1:7001 0.0.0.0:* LISTEN 61024/redis-server
tcp 0 0 127.0.0.1:7002 0.0.0.0:* LISTEN 61029/redis-server
1
2
3
4
5
6
7
8
9
10
11
12
13
##另外一台机器
ps -ef | grep redis
root 9957 1 0 02:32 ? 00:00:01 redis-server 127.0.0.1:7003 [cluster]
root 9964 1 0 02:32 ? 00:00:01 redis-server 127.0.0.1:7004 [cluster]
root 9971 1 0 02:32 ? 00:00:01 redis-server 127.0.0.1:7005 [cluster]
root 10065 4744 0 02:38 pts/0 00:00:00 grep --color=auto redis
netstat -tlnp | grep redis
tcp 0 0 127.0.0.1:17003 0.0.0.0:* LISTEN 9957/redis-server 1
tcp 0 0 127.0.0.1:17004 0.0.0.0:* LISTEN 9964/redis-server 1
tcp 0 0 127.0.0.1:17005 0.0.0.0:* LISTEN 9971/redis-server 1
tcp 0 0 127.0.0.1:7003 0.0.0.0:* LISTEN 9957/redis-server 1
tcp 0 0 127.0.0.1:7004 0.0.0.0:* LISTEN 9964/redis-server 1
tcp 0 0 127.0.0.1:7005 0.0.0.0:* LISTEN 9971/redis-server 1
7.创建集群
Redis 官方提供了 redis-trib.rb 这个工具，就在解压目录的 src 目录中，第三步中已将它复制到 /usr/local/bin 目录中，可以直接在命令行中使用了。使用下面这个命令即可完成安装。
redis-trib.rb create --replicas 1 192.168.31.245:7000 192.168.31.245:7001 192.168.31.245:7002 192.168.31.210:7003 192.168.31.210:7004 192.168.31.210:7005
其中，前三个 ip:port 为第一台机器的节点，剩下三个为第二台机器。
等等，出错了。这个工具是用 ruby 实现的，所以需要安装 ruby。安装命令如下：
yum -y
install
ruby ruby-devel rubygems rpm-build
gem install redis
之后再运行 redis-trib.rb 命令，会出现如下提示：
输入 yes 即可，然后出现如下内容，说明安装成功。
8. 集群验证
在第一台机器上连接集群的7002端口的节点，在另外一台连接7005节点，连接方式为 redis-cli -h192.168.31.245 -c -p 7002 ,加参数 -C 可连接到集群，因为上面 redis.conf 将 bind 改为了ip地址，所以 -h 参数不可以省略。
在7005节点执行命令 set hello world ，执行结果如下：
然后在另外一台7002端口，查看 key 为 hello 的内容， get hello ，执行结果如下：
说明集群运作正常。
简单说一下原理
redis cluster in the design, to take into account to the center, to the middleware, that is, each node in the cluster are equal relationship are peers, each node keeps their data and entire the state of the cluster. Each node and all other nodes are connected, and these connections remain active, thus ensuring that we only need to connect any node in the cluster, you can get the data to other nodes.
Redis cluster and does not use the traditional consistent hashing to distribute data, instead of using another known 哈希槽 (hash slot)way to distribution. redis cluster 16384 slot allocated by default, when we set a key, will use CRC16algorithms to obtain modulo belongs slot, then the node key assigned to the hash slot interval, the specific algorithm is:CRC16(key) % 16384。所以我们在测试的时候看到set 和 get 的时候，直接跳转到了7000端口的节点。
Redis cluster data will present a master node, then the data synchronization between the master and its corresponding salve. When reading data, also corresponding to the master node acquires data according to a consistent hashing algorithm. After only hang up when a master, will start a salve nodes corresponding to serve as master.
Note that: You must be 3个或以上the primary node, or when creating a cluster fail, and when the survival of the main nodes less than half of the total number of nodes, the entire cluster will not be able to provide the service.