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Scale a Redis cluster
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Scale a Redis cluster

A Redis cloud database cluster is scalable. For example:

  • Increase RAM to improve cluster performance;
  • change a fixed node configuration to another fixed configuration — disk and RAM size must necessarily be larger than in the previous configuration, the number of vCPUs can be reduced or increased.

Look at the list of node configurations.

The process of reconfiguration depends on the availability of replicas.

Principle of operation⁠

The process of changing the configuration depends on the availability of replicas:

  • if there are no replicas in the cluster — the master node will be stopped while the changes are applied, the cluster will be temporarily unavailable for reading and writing;
  • if there are replicas in the cluster — the cluster will be read and write accessible while the changes are being applied. The replicas will be stopped one by one and the configuration of each replica will be changed. The master node will then switch to one of the replicas and the configuration of the past master node will be changed.

The configuration change time depends on the amount of data in the cluster.

Scale up the cluster⁠

  1. Scale the cluster when users are least active.
  2. To avoid stopping the master node in a cluster without replicas, add a replica. After scaling, the replica can be removed.
  3. In the Dashboard, on the top menu, click Products and select Cloud Databases.
  4. Open the Active tab.
  5. Open the cluster page → Settings tab.
  6. Click Change Configuration.
  7. Select another fixed configuration. You can only select a configuration with more RAM and disk space. The number of vCPUs can be reduced or increased.
  8. Optional: increase the number of replicas in the cluster.
  9. Click Save.
  10. After scaling , clear the DNS cache.
  11. Verify that the cluster has scaled correctly.

Clear DNS cache⁠

  1. Open the CLI.

  2. Clear the DNS cache:

    sudo systemctl restart systemd-resolved