[redis] redis high availability deployment scheme in distributed scenarios

1、Redis High availability Overview

Refer to the post ：

• Learn more Redis
• Interview questions ： Yours Redis How to do persistence ？

Introducing Redis Before high availability , First of all, let's explain that in Redis The meaning of high availability in the context of .

We know , stay web Server , High availability refers to the time when the server can be accessed normally , The measure is how long a normal service can be provided （99.9%、99.99%、99.999% wait ）. But in Redis In context , The meaning of high availability seems to be broader , In addition to ensuring normal service （ Such as Master slave separation 、 Rapid disaster recovery technology ）, We also need to consider the data capacity Expand 、 Data security will not be lost etc. .

stay Redis in , Technologies to achieve high availability mainly include Persistence 、 Copy 、 sentry and colony , Their functions are described below , And what kind of problems have been solved .

• Persistence ： Persistence is the simplest high availability method （ Sometimes it's not even classified as a highly available means ）, The main functions are The data backup , Store data on hard disk , Ensure that data is not lost due to process exit .
• Copy ： Copy is Redis High availability Foundation , Sentinels and clusters are highly available based on replication . Replication mainly realizes data Multi machine backup （ Solve the single point of failure problem ）, And for Load balancing for read operations and Simple fault recovery . defects ： Failure recovery cannot be automated ; Write operations are not load balanced ; Storage capacity is limited by a single machine .
• sentry ： On the basis of replication , The Sentinels achieved Automated fault recovery . defects ： Write operations are not load balanced ; Storage capacity is limited by a single machine .
• colony ： By clustering ,Redis It solves the problem that write operation cannot be load balanced , And storage capacity is limited by single machine , A relatively complete high availability scheme has been realized .

2、 Persistence

3、Redis Master slave copy

utilize docker Start two redis example

#  Pull redis Mirror image 
​docker pull redis:5.0.0
#  create profile 
​touch /docker/redis/conf/redis.conf
#  Start mirror container 
docker run -p 6379:6379 --name redis \
-v /docker/redis/data:/data \
-v /docker/redis/conf/redis.conf:/etc/redis/redis.conf \
-d redis:5.0.0 redis-server   
#  Turn on self starting 
​docker update redis --restart=always

The server ip by 172.16.31.128 Respectively mapped in 6379（ Lord ） and 6380（ from ） Under port （ The default is the master node ）

Realization way

We need to pay attention to , The opening of master-slave replication , It's all from the node ; We don't need to do anything at the master node .

Enable master-slave replication from the slave node , Yes 3 Ways of planting ：

• The configuration file . Add to profile from server ：slaveof <masterip> <masterport>
• Start command .redis-server Add after starting command --slaveof <masterip> <masterport>
• Client commands .Redis After the server starts , Execute commands directly from the client ：slaveof , Then Redis Instance becomes slave .

Above 3 This is equivalent to , Take the client command as an example , Take a look at the execution of slaveof after ,Redis Changes in master and slave nodes .

Input from the node slaveof command , Join the master node

Add hello ——> world

The slave node can get come out , It shows that the master and subordinate are ok ！！！

View the slave node after deletion , It is found that the slave node is also deleted synchronously .

Can pass slaveof no one Command to disconnect all master-slave connections

4、Redis Sentinel mode

3、Redis Cluster pattern