Automatically adjust the bandwidth of a Redis instance - Database Autonomy Service

Database Autonomy Service (DAS) automatically adjusts the bandwidth of a Redis instance by upgrading or downgrading bandwidth based on real-time average bandwidth usage, helping you handle planned or unexpected traffic spikes.

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

Each instance type has a specific bandwidth limit. If traffic exceeds this limit, network congestion may degrade service performance. During traffic peaks or temporary increases in read/write operations on large keys, you can adjust the bandwidth to quickly eliminate bottlenecks without changing the instance type. Bandwidth adjustment is more cost-effective than an instance type change and takes effect immediately without causing transient connections. For more information, see Manually adjust the bandwidth of a Redis instance.

How it works

The system keeps actual bandwidth usage between the increase threshold and the decrease threshold you set — similar to a thermostat that maintains temperature within a target range. When usage crosses a threshold, the system calculates a new target bandwidth and scales accordingly.

Scaling formula:

Target bandwidth (MB/s) = Actual bandwidth usage (MB/s) / ((Increase threshold + Decrease threshold) / 2)

Example: An instance has a default bandwidth of 96 MB/s, an increase threshold of 70%, a decrease threshold of 30%, and an observation window of 15 minutes.

When Average Bandwidth Usage >= 70%, the system scales up: target bandwidth = (96 × 70%) / ((70% + 30%) / 2) = 135 MB/s.
If Average Bandwidth Usage then drops to <= 30%, the system scales back down to the default (96 MB/s minimum).

Scaling limits:

Maximum increase: 6x the instance's default bandwidth, up to a maximum increment of 192 MB/s
Minimum after decrease: the default bandwidth of the instance type

Behavior by architecture

Architecture	Scaling behavior
Cloud Native read/write splitting	Scales bandwidth of all nodes based on the node with the highest bandwidth usage
Cluster or Classic read/write splitting	Monitors and scales at the data shard or read replica level; each node scales independently

Use cases

Scenario	Description
Handle traffic spikes	Temporarily increase bandwidth during flash sales or planned high-traffic events, then scale back down to reduce costs.
Mitigate big key impacts	When many read/write operations on big keys create short-term bandwidth pressure, auto scaling buys time while you address the underlying issue.
Handle request skew in distributed architectures	In cluster or read/write splitting architectures, some data shards or read replicas can hit their bandwidth limits while others remain idle. Auto scaling increases bandwidth only for the hot nodes, avoiding the need to upgrade the entire instance.

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

Extra bandwidth is billed hourly based on the amount and duration. 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 reaches or exceeds 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 reaches or exceeds 70% within a 30-minute observation window, the system upgrades the bandwidth of 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 drops to or below 30%, the system downgrades the bandwidth 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 drops to or below 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: Click Event Subscription Settings to configure event notifications for automatic bandwidth upgrades or downgrades.
When an automatic bandwidth upgrade or downgrade occurs, DAS generates a Notification-level event. Turn on the Enable Subscription Service switch and configure event notification parameters. For more information, see Enable event subscription.
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. 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 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.