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This article is about how to build a redis cluster. The editor thought it was very practical, so I shared it with you as a reference. Let's follow the editor and have a look.

Introduce the installation environment and version

Two virtual machines are used to simulate 6 nodes and a machine with 3 nodes to create a 3 master, 3 salve environment.

Redis uses the redis-3.2.4 version.

Both virtual machines are CentOS, one CentOS6.5 (IP:192.168.31.245) and one CentOS7 (IP:192.168.31.210).

Installation process

1. Download and decompress

Cd / root/softwarewget http://download.redis.io/releases/redis-3.2.4.tar.gztar-zxvf redis-3.2.4.tar.gz

two。 Compilation and installation

Cd redis-3.2.4make & & make install

3. Copy redis-trib.rb to the / usr/local/bin directory

Cd srccp redis-trib.rb / usr/local/bin/ 4. Create a Redis node

First create the redis_cluster directory on the 192.168.31.245 machine under the / root/software/redis-3.2.4 directory

Mkdir redis_cluster

Under the redis_cluster directory, create directories named 7000, 7001, 7002, and copy redis.conf to these three directories

Mkdir 7000 7001 7002

Cp redis.conf redis_cluster/7000cp redis.conf redis_cluster/7001cp redis.conf redis_cluster/7002

Modify the three configuration files respectively, and modify the following

Port 7000 / / Port 7000Magol 7002Magol 7003 bind Native ip / / default ip is 127.0.0.1 need to be changed to ip accessible to other node machines, otherwise the corresponding port cannot be accessed when creating a cluster Unable to create cluster daemonize yes / / redis background run pidfile / var/run/redis_7000.pid / / pidfile file corresponding to 7000Magi 7001j7002clusterwords enabled yes / / enable cluster to comment # remove cluster-config-file nodes_7000.conf / / configuration file of the cluster for the first time start automatic generation of 7000meme7001j7002clustercolor node7001Power7002clusterwords- Timeout 15000 / / request timeout defaults to 15 seconds You can set the appendonly yes / / aof log to enable it if necessary. It will record a log for each write operation.

Then, on another machine (192.168.31.210), repeat the above three steps, only change the directory to 7003, 7004, 7005, and modify the corresponding configuration file according to this rule.

5. Start each node

Execute redis-server redis_cluster/7000/redis.confredis-server redis_cluster/7001/redis.confredis-server redis_cluster/7002/redis.conf on the first machine and redis-server redis_cluster/7003/redis.confredis-server redis_cluster/7004/redis.confredis-server redis_cluster/7005/redis.conf on the other machine

6. Check redis startup

# # one machine

Ps-ef | grep redisroot 61020 10 02:14? 00:00:01 redis-server 127.0.0.1 grep redisroot 7000 [cluster] root 61024 02:14? 00:00:01 redis-server 127.0.1 root 61029 10 02:14? 00:00:01 redis-server 127.0.1 grep redisroot 7002 [cluster] netstat -tnlp | grep redistcp 00 127.0.0.1 LISTEN 61020/redis-server tcp 17000 0.0.0.0 LISTEN 61020/redis-server tcp 00 127.0.0.1 LISTEN 61020/redis-server tcp 17001 0.0.0.0 LISTEN 61024/redis-server tcp 00 127.0.0.1 LISTEN 61020/redis-server tcp 17002 0.0.0.0 LISTEN 61029/redis-server tcp 00 127.0.0.1 7000 0.0.0.0 LISTEN 61020/redis-server tcp 00 127.0.0.1 7001 0.0.0.0 LISTEN 61024/redis-server tcp 00 127.0.0.1 LISTEN 61024/redis-server tcp 7002 0.0.0.0 * LISTEN 61029/redis-server12345678910111213 # # another machine ps-ef | grep redisroot 9957 10 02:32? 00:00:01 redis-server 127.0.0.1 LISTEN 61024/redis-server tcp 7003 [cluster] root 9964 10 02 32? 00:00:01 redis-server 127.0.0.1 redis-server 7004 [cluster] root 9971 10 02:32? 00:00:01 redis-server 127.0.0.1 root 7005 [cluster] root 10065 4744 0 02:38 pts/0 00:00:00 grep-- color=auto redisnetstat-tlnp | grep redistcp 00 127.0.0.1 root 17003 0.0.0.0 : * LISTEN 9957/redis-server 1tcp 00 127.0.0.1 LISTEN 9971/redis-server 1tcp 17004 0.0.0.0 LISTEN 9971/redis-server 1tcp 00 127.0.0.1 LISTEN 9971/redis-server 1tcp 00 17005 0.0.0.0 .1 LISTEN 9957/redis-server 1tcp 7003 0.0.0.0 LISTEN 9971/redis-server 00 127.0.0.1 LISTEN 9971/redis-server 00 7004 0.0.0.0 LISTEN 9971/redis-server 17. Create a cluster

Redis officially provides redis-trib.rb, which is in the src directory of the unzipped directory. In the third step, you have copied it to the / usr/local/bin directory, which can be used directly on the command line. Use the following command to complete the installation.

Redis-trib.rb create-- replicas 1 192.168.31.245Viru 7000 192.168.31.245Vera 7002 192.168.31.245Vera 7002 192.168.31.210VlV 7003 192.168.31.210VlV 7004 192.168.31.210Rd 7005

The first three ip:port are the nodes of the first machine, and the remaining three are the second machine.

Wait, something went wrong. This tool is implemented in ruby, so you need to install ruby. The installation commands are as follows:

Yum-y install ruby ruby-devel rubygems rpm-build

Gem install redis

After running the redis-trib.rb command, the following prompt appears:

Just enter yes, and then the following appears to indicate that the installation is successful.

8. Cluster verification

Connect the node at port 7002 of the cluster on the first machine, and connect 7005 nodes on the other. The connection method is redis-cli-h 192.168.31.245-c-p 7002. Add the parameter-C to connect to the cluster. Because the above redis.conf changes bind to ip address, the-h parameter cannot be omitted.

Execute the command set hello world on node 7005, and the result is as follows:

Then, on another port 7002, check the content where key is hello, get hello, and the execution result is as follows:

It indicates that the cluster is operating normally.

A brief description of the principle.

When redis cluster is designed, it takes into account decentralization and middleware, that is, each node in the cluster is equal and peer-to-peer, and each node saves its own data and the state of the whole cluster. Each node is connected to all other nodes, and these connections remain active, which ensures that we only need to connect to any node in the cluster to get the data of other nodes.

Instead of using traditional consistent hashes to allocate data, Redis clusters allocate data in another way called hash slot. Redis cluster allocates 16384 slot by default. When we set a key, we use the CRC16 algorithm to get the slot we belong to, and then assign the key to the nodes in the hash slot. The specific algorithm is: CRC16 (key)% 16384. So when we saw set and get during the test, we jumped directly to the node on port 7000.

The Redis cluster stores the data in a master node and then synchronizes the data between the master and its corresponding salve. When the data is read, the data is also obtained from the corresponding master node according to the consistent hashing algorithm. Only when a master is dead will a corresponding salve node be started to act as a master.

It should be noted that there must be 3 or more master nodes, otherwise the creation of the cluster will fail, and when the number of surviving master nodes is less than half of the total number of nodes, the entire cluster will not be able to provide services.

Thank you for reading! On how to build the redis cluster to share here, I hope the above content can be of some help to you, so that you can learn more knowledge. If you think the article is good, you can share it and let more people see it.

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