CODEWITHSUNDEEP
redisnosqlmaster-slave
Saisumanth Gopisetty
Saisumanth Gopisetty

Reputation: 946

What happens to data before new master is elected in Redis?

In redis master-slave architecture, when a master fails a slave is promoted to master. As only master can perform write operations, What happens to data in the window period when slave is promoted to master. Does my system remain unresponsive?

Upvotes: 0

Views: 133

Answers (1)

Itamar Haber
Itamar Haber

Reputation: 50102

Define "data":)

Client connections to the master will be closed upon its failure, so your system will be notified of that. Any data that was not written to the master and the replicas before the failure will therefore still reside in your application/system.

Once your system tries using a replica it will be able to read the data in it up to the point it was synchronized before failure. Once the replica is promoted to masterhood, your system will be able to continue writing data.

Note that Redis' synchronization is asynchronous. That means that slaves may lag behind the master and therefore lose some updates in case of failure. Refer to the WAIT command for more information about ensure the consistency.

Upvotes: 2

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