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

Prerequisites

The instance is an ApsaraDB for Redis Community Edition instance, or a performance-enhanced or hybrid-storage instance of ApsaraDB for Redis Enhanced Edition (Tair).

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 the performance of the instance may deteriorate. To prevent these situations, you can enable the bandwidth auto scaling feature. Compared with an instance specification change, a bandwidth adjustment helps you increase the bandwidth at lower costs and prevent transient connections.

Scenario Description
Flexibly handle traffic spikes The bandwidth auto scaling feature adjusts the bandwidth of an ApsaraDB for Redis instance based on your business requirements. For example, this feature increases the bandwidth during a flash sale during which traffic spikes are scheduled. After the flash sale ends, this feature decreases the bandwidth to reduce costs.
Mitigate impacts on your business If a large number of read and write operations are performed on big keys within a short period of time, this feature temporarily increases the bandwidth of the instance to mitigate impacts on your business and to reserve time to process operations on big keys.
Deal with skewed requests at low costs If your instance is in the cluster or read/write splitting architecture, some data shards or read replicas of the instance are frequently accessed. As a result, the bandwidth in use of these data shards or read replicas frequently reaches the allocated bandwidths. However, the usage of the bandwidths that are allocated to the 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 bandwidth is insufficient and automatically increases the bandwidth for them. You do not need to increase the bandwidth or change the specifications of the instance. This reduces costs and facilitates O&M.

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 increase or decrease amount is calculated by the system.

  • If the bandwidth increase threshold of an instance is reached, the system automatically 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 the 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 is in 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 in the notification method that you select, such as an email. For more information about how to enable the subscription service, see the relevant section in this topic.
  • To ensure that DAS can access resources of your ApsaraDB for Redis instance, the system authorizes DAS to use 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. Then, you can increase the bandwidth of the instance to a higher value. If the increased bandwidth is still insufficient, submit a ticket.
    Note
    • For more information about the maximum bandwidth values supported by different instance specifications, 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 automatically becomes invalid and you will receive a refund. You must re-adjust the bandwidth of the instance based on your business requirements. By default, the expiration time of the previously purchased extra bandwidth is inherited.
    Operation Exception
    Upgrade the major version N/A
    Change the configurations of an instance If the instance is a standard instance, the bandwidth settings remain valid after you change the specifications of the instance.
    Migrate an instance across zones If the instance is a standard instance, the bandwidth settings remain valid.

Pricing

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 and prices.

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.
  2. In the top navigation bar of the page, select the region in which the instance is deployed.
  3. On the Instances page, click the ID of the instance.
  4. Click the Edit icon next to Bandwidth Auto Scaling.
    Figure 1. Bandwidth Auto Scaling
    Bandwidth Auto Scaling
  5. In the DAS console that appears, configure the policy for bandwidth auto scaling and event subscription.
    1. Configure the policy for bandwidth auto scaling.
      Figure 2. Configure the policy for bandwidth auto scaling
      Configure the policy for bandwidth auto scaling
      Section Parameter Description
      Automatic Bandwidth Upgrade Automatic Bandwidth Upgrade Turn on the switch to enable the feature.
      Average Bandwidth Usage Select the threshold of average bandwidth usage for triggering an automatic scale-up. Unit: percentage. 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 up to three times the default bandwidth value of the instance type. You can also view the message about this limit in the dialog box.
      Observation Window Select the period of the observation window. Unit: minutes.
      Note In this example, 15 minutes is selected. During this observation window, if the average bandwidth usage is equal to or greater than 70%, the bandwidth of the instance is increased. The increased amount is calculated by the system, and the bandwidth can be increased up to three times the default bandwidth of the instance type. If the average bandwidth usage is equal to or smaller than 30%, the bandwidth is decreased. The decreased amount 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 Turn on the switch to enable the feature. Before you enable this feature, make sure Automatic Bandwidth Upgrade is turned on.
      Average Bandwidth Usage Select the threshold of average bandwidth usage for triggering an automatic scale-down. Unit: percentage. 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 to configure the event subscription.
      Figure 3. Configure the event subscription
      Configure the event subscription
      Parameter Description
      Enable Subscription Service Turn on the switch to enable the feature. If an event of the specified level or a higher level occurs, DAS notifies you of the event by using the specified method, such as an 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 the specified level or a higher level occurs, DAS sends a notification. Valid values:
      • Critical: the events that affect the operating of the database.
      • Warning: the events that may affect the operating of the database.
      • Optimize: the events for which optimization suggestions are generated based on the status of the database.
      • Notification: the events about performance snapshots and the basic events.
      Note To subscribe to the events of bandwidth auto scaling, select the Notification level.
      Select Contacts/Contact Groups Select contacts or contact groups in the Existing Contacts/Contact Groups section and click the Right 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 a single method or a combination of methods. We recommend that you select a method that contains text message notification, which 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, if you set the interval to 5 minutes and the event occurs again after you receive the first notification about the event, you are notified again after 5 minutes.
  6. Click OK.

Result

Figure 4. The ApsaraDB for Redis console shows that the bandwidth auto scaling feature is enabled.
The ApsaraDB for Redis console shows that the bandwidth auto scaling feature is enabled.