Automatically adjust the bandwidth of a Redis instance-Database Autonomy Service(DAS)-阿里云帮助中心

Database Autonomy Service (DAS) lets you automatically adjust the bandwidth of a Redis instance, including automatic bandwidth upgrade and automatic bandwidth downgrade. DAS detects average bandwidth usage in real time to handle planned or unexpected traffic spikes, allowing you to focus on your business. This topic describes how to automatically adjust the bandwidth of a Redis instance.

Important

Auto scaling typically has a latency of 3 to 5 minutes. For highly sensitive business scenarios, lower the auto scaling thresholds and reduce the check frequency.
The auto scaling feature becomes unavailable if your account has an overdue payment. The feature resumes within three hours after your account returns to good standing.
The automatic bandwidth adjustment feature relies on real-time performance trend data to make scaling decisions. If this data is interrupted or significantly delayed, the feature may not function correctly.

Prerequisites

Open source Redis instances (in cloud-native or classic mode) with standard, cluster, or read/write splitting architectures.
Tair (Redis OSS-compatible) memory-optimized instances (in cloud-native or classic mode) with standard, cluster, or read/write splitting architectures.
Tair (Redis OSS-compatible) persistent memory-optimized instances with standard, cluster, or read/write splitting architectures.
A service-linked role for DAS is created.

Note
If you have not created a service-linked role for DAS, DAS automatically creates one for you before adjusting the bandwidth.

Background

The bandwidth of an instance varies based on its instance type. If traffic exceeds the bandwidth limit, network congestion may occur and degrade service performance. When you encounter traffic peaks or a temporary increase in read/write operations on large keys, you can adjust the instance bandwidth to quickly eliminate bottlenecks and prevent business disruptions. Compared to changing the instance type, adjusting the bandwidth is a more cost-effective way to quickly increase throughput. The adjustment takes effect immediately without causing transient connections. For more information, see Manually adjust the bandwidth of a Redis instance.

Use cases

You can use this feature to adjust instance bandwidth in the following business scenarios.

Detailed use cases

Scenario	Description
Flexibly handle traffic peaks	For example, if your business is expecting a traffic spike from a flash sale, you need to flexibly increase bandwidth to handle the load and then decrease it afterward to save costs.
Quickly mitigate business impact from bandwidth limitations	For example, when a temporary increase in read/write operations on large keys occurs, you need to quickly remove bandwidth limits to avoid affecting your business and allow time to address the large key issue.
Cost-effectively manage skewed access patterns	For instances that use a cluster architecture or a read/write splitting architecture, some data shards or read-only nodes may experience high traffic and frequently reach their bandwidth limits while other nodes remain underutilized. When this feature is enabled, the system identifies the specific data shards or read-only nodes that require more bandwidth and automatically upgrades their bandwidth. This eliminates the need to upgrade the entire instance, which significantly reduces costs and simplifies O&M.

How auto scaling works

After you enable this feature, DAS acts as follows based on the auto scaling policy and observation window that you configure. The system automatically calculates the amount of bandwidth to add or remove.

When the scale-up threshold is met: DAS increases the instance bandwidth and continues to monitor its usage. If the threshold is met again, DAS increases the bandwidth again. The additional bandwidth can be increased by up to six times the default bandwidth of the instance, with a maximum total increase of 192 MB/s.
If you require more bandwidth, we recommend using Tair (Enterprise Edition). All Tair instance types provide a maximum bandwidth of at least 96 MB/s. You can also upgrade to Tair (Enterprise Edition) and then adjust the bandwidth.
When the scale-down threshold is met: DAS reduces the instance bandwidth and continues to monitor its usage. If the threshold is met again, DAS continues to reduce the bandwidth. The bandwidth can be reduced to the default bandwidth of the instance type.

Note

The target bandwidth for each scaling event is calculated using the following formula: Actual bandwidth usage (MB/s) / ((Scale-up threshold + Scale-down threshold) / 2). After each scaling event, the system attempts to keep the actual bandwidth utilization between the scale-up and scale-down thresholds.

For example, if an instance has a default bandwidth of 96 MB/s and you set the scale-up threshold to 70%, the scale-down threshold to 30%, and the Observation Window to 15 minutes, a scale-up operation is triggered when the average bandwidth usage is greater than or equal to 70%. The target bandwidth after the scale-up is ((96 MB/s × 70%)) / ((70% + 30%) / 2) = 135 MB/s. If the average bandwidth usage is less than or equal to 30% of the upgraded bandwidth, the system performs a scale-down operation on the instance, scaling it down to a minimum of the default bandwidth for the current instance type.

Limitations

After an automatic scale-up, the system waits at least 1 hour before triggering an automatic scale-down.
There is a 1-minute cooldown between two consecutive automatic scale-up operations.
Bandwidth can be increased by up to 6x the default bandwidth of the instance type, with a maximum increment of 192 MB/s. Examples: If you need higher bandwidth than these limits allow, consider upgrading to Tair (Enterprise Edition), where each instance type supports a maximum bandwidth of at least 96 MB/s. You can also upgrade the instance type or switch to a cluster architecture. See Instance types for details.
- A 2 GB standard Tair memory-optimized instance has a default bandwidth of 96 MB/s. Its maximum bandwidth is 96 + 192 = 288 MB/s.
- A 256 MB standard Redis Community Edition instance has a default bandwidth of 10 MB/s. The maximum additional bandwidth is 60 MB/s, so the maximum is 70 MB/s.
Do not manually adjust instance bandwidth while bandwidth auto scaling is enabled. The two features interact as follows: Examples:
- Default bandwidth: 10 MB/s, manually set to 70 MB/s — scale-up is never triggered (already at the 6x limit).
- Default bandwidth: 10 MB/s, manually set to 40 MB/s — scale-up can increase to 70 MB/s; scale-down reduces to 10 MB/s.
If the instance has unexpired bandwidth plans, you cannot enable bandwidth auto scaling. First unsubscribe from those plans. See Unsubscription management.

The following operations disable bandwidth auto scaling. Re-enable the feature afterward if needed:

Operation	Exception
Major version upgrade	None
Change the configurations of an instance	For standard architecture instances, bandwidth settings remain valid after a spec change.
Change the zone of an instance	For standard architecture instances, bandwidth settings remain valid after a zone migration.

Billing

You are charged on an hourly basis for the amount and duration of the extra bandwidth. The fees vary by region. For more information, see Billable items.

Note

You are not charged for the default bandwidth. You are charged only for the additional bandwidth.

Procedure

Log on to the DAS console.
In the navigation pane on the left, click Intelligent O&M Center > Instance Monitoring .
Find the target instance and click the instance ID to open the instance details page.
In the navigation pane on the left, click Autonomy Center. In the upper-right corner of the page, click Autonomy Service Settings.

On the Autonomous Function Management > Autonomous Function Settings tab, turn on the switch for the autonomy service and configure the parameters for Automatic Bandwidth Upgrade and Automatic Bandwidth Downgrade.

On the Optimization and Throttling tab, select the checkboxes for Automatic Bandwidth Extension and Automatic Bandwidth Scale-back.

Category	Parameter	Description
Automatic Bandwidth Extension	Automatic Bandwidth Extension	Select the checkbox to enable this feature.
	Average Bandwidth Usage ≥	When the average bandwidth usage is greater than or equal to this threshold, an automatic bandwidth upgrade is triggered. The value is a percentage. The average bandwidth usage is the larger of the average inbound and outbound bandwidth.
	Observation Period	Select the duration of the observation window. Unit: minutes. Note With the example settings, if the average bandwidth usage is greater than or equal to 70% within a 30-minute observation window, the system performs a bandwidth upgrade operation on the Redis instance. The additional bandwidth can be increased by up to six times the instance's default bandwidth, with a maximum increase of 192 MB/s. If the average bandwidth usage is less than or equal to 30%, the system performs a bandwidth downgrade operation. The bandwidth can be decreased to the default bandwidth of the current instance type.
Automatic Bandwidth Scale-back	Automatic Bandwidth Scale-back	Select the checkbox to enable this feature. You can enable Automatic Bandwidth Scale-back only after you enable Automatic Bandwidth Extension.
Automatic Bandwidth Scale-back	Average Bandwidth Usage ≤	When the average bandwidth usage is less than or equal to this threshold, an automatic bandwidth downgrade is triggered. The value is a percentage. The average bandwidth usage is the smaller of the average inbound and outbound bandwidth.

Click OK.
Optional: Configure an Alert Template to subscribe to alerts to stay informed about the automatic bandwidth adjustments of your database instance.

The system recommends an alert template and adds alert rules for the corresponding autonomy events. You can follow the prompts to complete the configuration.
Note
- If you have already configured an alert template for the instance, follow the prompts to add the corresponding alert rules for the autonomy events to the template.
- If you need to configure an alert template and alert rules yourself, see Configure alert templates and Configure alert rules.
Select an Alert Contact Group to receive alert notifications.
- Click Add Contact to add a new alert contact.
- Click Create Contact Group to create a new alert contact group.
- Click Modify or Remove next to a contact to modify or delete the contact.
For more information, see Manage alert contacts.
Click Submit Configuration, and then confirm the alert configuration in the dialog box.

API reference

API	Description
EnableAdditionalBandwidth	Manually adjusts the bandwidth of a Redis instance.