Redis5.0 slot migration, free play (single machine migration cluster)

        Recently doing redis The stand-alone version is migrated to the cluster version , So it was used redis3.0 Version , There was a problem during the migration , Is that if redis5.0 Previous version , When moving the slot point , If there is a value in the slot , Result in an error ：Syntax error ,try client(list|kill|getname|setname|pause|reply)  , It mainly needs to be modified redis-trib.rb Of documents move_slot This method , Bypass clientCommand, Direct execution migrateCommand（ Get rid of .client that will do ）. Here's the picture

After the modification , Can reshard With data slot There's a slot . If not modified trib file , There was a mistake in the above （Syntax error ,try client）, At this time, the slot with data , Will also be immovable .  perform cluster setlot The value of the slot point stable that will do .

The above is just that I have operated redis3.0 Problems and solutions during data migration . Let's talk about it redis5.0 after , operation slot The order of , Get along well with redis5.0 A cinch .

First of all, our redis It is the cluster version , Three masters and three followers , I won't talk about it here redis Of sentinel Sentinel mode （ monitor , remind , Automatic failover has several features ）.

Directly above

redis5.0 The version abandoned trib file , change to the use of sth. redis-cli Operation cluster , This is also a lot of improvement and optimization .

You can see redis Version of .

redis-cli --cluster check host:port This command can view the information of each node of the cluster .

Now let's start 7002 and 7003 All slot points of are moved to 7001 On ：

Ask how many slot points to move , We move 7002 All ,5462 individual

 

And then 7003 All slot points of move to 7001 On

 

  At the moment ,7001 There are all the slots on the , Now students who want to migrate data , Just put the stand-alone version dump.rdb Copy the file to the cluster .

Let's start to divide the slot points equally ,

Use here rebalance When , because 7002 and 7003 There are no slots on it , So they do not participate in the election , Also cannot participate in the equalization slot point .

  We can use --cluster-use-empty-masters This parameter , Even if 7002 and 7003 No slot can participate in the equal distribution of slot points .

You can see that the slot points are evenly distributed , And the slave nodes are equally divided .

The one we circled can specify which master node the current slave node is under , Be free to distribute , Play around redis5.0 Slot point of . also forget, To delete a node , Other nodes have reserved information , There will still be heartbeat communication , Therefore, each reserved node is required , To carry out forget. There are other funny commands , I won't introduce them here . Thank you for coming .