The bandwidth auto scaling feature of Database Autonomy Service (DAS) is integrated into ApsaraDB for Redis. After you enable this feature for an ApsaraDB for Redis instance, DAS scales the instance bandwidth if the bandwidth usage of the instance reaches the specified threshold. This helps you handle unexpected or scheduled traffic spikes and focus on business improvement.

Prerequisites

An instance of the ApsaraDB for Redis Community Edition or a DRAM-based instance or hybrid-storage instance of the ApsaraDB for Redis Enhanced Edition (Tair) is created. For more information about DRAM-based instances and hybrid-storage instances, see DRAM-based instances and Hybrid-storage instances (phased out).

Scenarios

The bandwidth of an instance varies based on the instance type. If the bandwidth in use reaches the allocated bandwidth, network congestion may occur and instance performance may deteriorate. To prevent these situations, you can enable the bandwidth auto scaling feature. A bandwidth adjustment helps you increase bandwidth at a lower cost than an instance specification change and can help prevent transient connections.

Note If the instance is a Community Edition instance that requires a sharp bandwidth increase, we recommend that you change the instance into an Enhanced Edition (Tair) instance. This is because a Tair instance can support a bandwidth of 96 Mbit/s or more.
Scenario Description
Handle traffic spikes You can adjust the bandwidth of the instance to handle traffic spikes during promotional events such as a flash sale. After these events end, you can decrease the bandwidth of the instance to reduce costs.
Mitigate impacts on your business If a large number of read and write operations are performed on large keys within a short period of time, you must temporarily increase the bandwidth of the instance to mitigate impacts on your business and to reserve time for processing these operations.
Deal with request skew at low costs If your instance uses the cluster or read/write splitting architecture, specific data shards or read replicas of the instance are more frequently accessed than others. As a result, the bandwidth consumption of these data shards or read replicas frequently reaches the allocated bandwidths. However, the usage of the bandwidths that are allocated to other data shards or read replicas is low.

After you enable the bandwidth auto scaling feature, the system identifies the data shards or read replicas whose allocated bandwidths are insufficient and increases the bandwidths for them. You do not need to manually increase the bandwidth or change the specifications of the instance to which these data shards or read replicas belong. This reduces costs and facilitates O&M.

Auto bandwidth scaling process

After you enable the bandwidth auto scaling feature, the system automatically performs the following operations based on the auto scaling policy and observation window that you configure. The increment or decrement is calculated by the system.

  • If the bandwidth increase threshold of an instance is reached, the system increases the bandwidth and continues to monitor bandwidth usage. If the threshold is reached again, the system increases the bandwidth again. The bandwidth can be increased up to three times the default bandwidth of the instance type. If you want to increase this bandwidth limit, you can upgrade the specifications of your instance and then adjust the bandwidth.
  • If the bandwidth decrease threshold of an instance is reached, the system decreases the bandwidth and continues to monitor bandwidth usage. If the threshold is reached again, the system decreases the bandwidth again. The bandwidth can be decreased to the default bandwidth of the instance type.
Note
  • If your instance uses the cluster or read/write splitting architecture, the system monitors the bandwidth usage of data shards and read replicas and increases the bandwidth only for the data shards or read replicas whose allocated bandwidth is insufficient.
  • If you enable the subscription service, you are notified of every increase or decrease by the notification method that you select, such as an email. For more information about how to enable the subscription service, see the "Procedure" section of this topic.
  • To ensure that DAS can access resources of your ApsaraDB for Redis instance, the system authorizes DAS to assume the AliyunServiceRoleForDAS role after you enable this feature.

Limits

  • The bandwidth of an instance can be increased to up to three times the bandwidth that is provided for the instance type. If you require higher bandwidth for an instance, you can change the specifications of the instance or upgrade the instance from a standard instance to a cluster instance, and then adjust the instance bandwidth.
    Note
    • For more information about the bandwidths that are supported by different instance types, see Overview.
    • If you change the architecture of an instance, such as from standard to cluster, you can no longer use the bandwidth auto scaling feature.
  • If you perform the following operations on an instance, the extra bandwidth that you purchased becomes invalid and you receive a refund. You must re-adjust the instance bandwidth based on your business requirements. By default, the adjusted bandwidth inherits the expiration time of the previously purchased extra bandwidth.
    Operation Exception
    Upgrade the major version None
    Change the configurations of an instance If the instance is a standard instance, the bandwidth settings remain valid after you upgrade the specifications of the instance.
    Migrate an instance across zones If the instance is a standard instance, the bandwidth settings remain valid.

Billing

You are charged per day based on the amount and usage duration of the extra bandwidth that you purchase. The fees vary based on the region that you select. For more information, see Billable items.

Note You are not charged for the bandwidth that is provided for the instance type. You are charged only for the extra bandwidth that you purchase.

Procedure

  1. Log on to the ApsaraDB for Redis 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 Basic Information section, click Modify next to Bandwidth Auto Scaling.
    The first time you log on to the DAS console, follow the instructions to grant permissions to your account.
  3. In the DAS console, configure the policy for bandwidth auto scaling and event subscription.
    1. Configure the policy for bandwidth auto scaling.
      Category Parameter Description
      Automatic Bandwidth Upgrade Automatic Bandwidth Upgrade Click the check box to enable the feature.
      Average Bandwidth Usage Select the threshold of average bandwidth usage for triggering an automatic scale-up. Valid values: 50% to 95%.
      Note
      • The system compares the bandwidth usage of inbound traffic and that of outbound traffic, and takes the larger value as the average bandwidth usage.
      • The bandwidth of an ApsaraDB for Redis instance can be increased to up to three times the default bandwidth value of the instance type. You can also view the note about this limit in the dialog box.
      Observation Window Select the period of the observation window. Unit: minutes.

      In this example, 15 minutes is selected. During this observation window, if the average bandwidth usage is greater than or equal to 70%, the bandwidth of the instance is increased. The increment is automatically calculated, and the bandwidth can be increased to up to three times the default bandwidth of the instance type. If the average bandwidth usage is less than or equal to 30%, the bandwidth is decreased. The decrement is calculated by the system, and the bandwidth can be decreased to the default bandwidth of the instance type.

      Automatic Bandwidth Downgrade Automatic Bandwidth Downgrade Click the check box to enable the feature. Before you enable this feature, make sure that the Automatic Bandwidth Upgrade feature is enabled.
      Average Bandwidth Usage Select the threshold of average bandwidth usage for triggering an automatic scale-down. Valid values: 10% to 30%.
      Note The system compares the bandwidth usage of inbound traffic and that of outbound traffic, and takes the smaller value as the average bandwidth usage.
    2. Optional: Click the Event Subscription Settings tab. On the Event Subscription Settings tab, configure the parameters as prompted.
      Parameter Description
      Enable Subscription Service Turn on Enable Subscription Service to enable the feature. If an event at the specified or higher level occurs, DAS uses the specified method such as an email to keep you informed. This ensures that you are notified when events occur on your instance.
      Urgency Select the lowest level of events for which DAS sends notifications. If an event of the specified level or a higher level occurs, DAS sends a notification. Valid values:
      • Critical: events that affect the running of the database.
      • Warning: events that may affect the running of the database.
      • Optimize: events about optimization suggestions are generated based on the running status of the database.
      • Notification: performance snapshot events and basic events.
      Note To subscribe to bandwidth auto scaling events, select the Notification level.
      Select Contacts/Contact Groups Select contacts or contact groups in the Existing Contacts/Contact Groups section and click the Rightwards arrow 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 Short Message Service (SMS) notification. This notification method has better timeliness.
      Notification Language Select a notification language. Valid values: Chinese and English.
      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.