Tair (Redis® OSS-Compatible):Enable automatic scale-up

Billing

You are charged only for the scale-up. For more information, see Configuration changes.

Process of automatic scale-up

Figure 1. Process of automatic scale-up

After the automatic scale-up feature is enabled for an instance, DAS monitors the average memory usage of the instance within the observation window. If the average memory usage reaches the specified threshold, DAS doubles the memory size of the instance, for example, from 1 GB to 2 GB. After the scale-up is complete, DAS continues to monitor the average memory usage. If the automatic scale-up condition is met again, DAS performs another scale-up of the instance until the specified maximum memory size is reached.

However, DAS does not directly scale down the instance. After you enable the subscription service, if the average memory usage of the instance drops below 30% within the observation window, DAS sends you a scale-down suggestion by using the specified notification method such as email. You can manually scale down the instance at an appropriate time to improve resource utilization. For more information about how to enable the subscription service, see the "Procedure" section of this topic.

Impacts of automatic scale-up

• If you change the configurations of an instance, the instance may experience one or two transient connections that each lasts up to 30 seconds.

• To synchronize incremental data from the original instance to the new instance and prevent dual writes caused by Domain Name System (DNS) caching, the instance remains read-only for up to 1 minute during the configuration change. This ensures data consistency between the new instance and the original instance.

• If the minor version of the instance is outdated, the system updates the instance to the latest minor version to ensure high performance and stability.

Procedure

1. Log on to the console and go to the Instances page. In the top navigation bar, select the region in which the instance is deployed. Then, find the instance and click its ID.

2. In the Configuration Information section, turn on Auto Scaling.

3. In the DAS console, configure the settings for automatic scale-up and event subscription.

   1. Choose Autonomous Function Settings > Optimization and Throttling, select Automatic Scale-up/out, and then configure automatic scale-up parameters.

      Parameter	Description
      Average Memory Usage	Select the threshold of average memory usage for triggering an automatic scale-up. Unit: percent (%). Valid values: 50 to 90. You can adjust the threshold at a step value of 10%.
      Maximum Specifications	Select the maximum memory size to which you can scale up the instance. If the average memory usage of the instance reaches the specified threshold, DAS doubles the memory size of the instance, for example, from 1 GB to 2 GB. After the scale-up is complete, DAS continues to monitor the average memory usage. If the automatic scale-up condition is met again, DAS performs another scale-up of the instance until the specified maximum memory size is reached.
      Observation Window	Select the length of the observation window. Unit: minutes. The maximum value is 30 minutes. Note In this example, if the average memory usage of the instance is greater than or equal to 70% within the 30-minute observation window, DAS scales up the instance by doubling its memory size. The memory size can be increased to up to 64 GB.

   2. (Optional) On the Event Subscription Settings tab, complete the settings as prompted.

      Parameter	Description
      Enable Subscription Service	Turn on the switch to enable the feature. If an event of a specified or higher level occurs, DAS notifies you of the event by using the specified method such as email. This ensures that you are notified at the earliest opportunity when events occur on your instance.
      Urgency	Select the lowest level of events for which DAS sends notifications. If an event of a specified or higher level occurs, DAS sends a notification. Valid values: Critical: events that affect the operation of databases. Warning: events that may affect the operation of databases. Optimize: events about optimization suggestions that are generated based on the status of your databases. Notification: basic events and events related to performance snapshots. Note To subscribe to automatic scale-up events and scale-down suggestions, select the Notification level.
      Select Contacts/Contact Groups	Select contacts or contact groups in the Existing Contacts/Contact Groups section and click the icon to move them to the Selected Contacts/Contact Groups section. Note If no contacts or contact groups are available, you must create a contact or contact group. For more information, see Manage alert contacts.
      Notification Method	Select a notification method. You can select one or more methods. We recommend that you select at least SMS to ensure timeliness.
      Notification Language	Select the language of notifications. Only Chinese is supported.
      Minimum Notification Interval	Select the minimum interval between two notifications about the same event. For example, you can set the interval to 5 minutes. In this case, if the event occurs again after you receive the first notification about the event, you are notified again 5 minutes later.

4. Click OK.

   Return to the console. On the details page of the instance, the switch corresponding to Auto Scaling is turned on.

FAQ

• Why is the automatic scale-up feature disabled after read/write splitting is enabled for a cluster instance?

  Only the standard architecture supports the automatic scale-up feature. Therefore, after read/write splitting is enabled for the cluster instance, the automatic scale-up feature is disabled.

References

Shards can be automatically added to Redis Open-Source Edition cloud-native cluster instances. For more information, see Automatic shard addition.