Traffic spikes from live streaming events, flash sales, or game launches can saturate your instance's fixed bandwidth within seconds, causing slow responses or connection drops. Burstable bandwidth automatically adds extra bandwidth when traffic exceeds your fixed allocation and releases it when traffic subsides — so you get the performance headroom you need without over-provisioning.
This feature is in public preview. To use this feature, submit a ticket to request access.
Key concepts
| Term | Definition |
|---|---|
| Fixed bandwidth | The total non-burstable bandwidth available to an instance. Includes the base bandwidth from the instance specification and any additionally purchased fixed bandwidth. |
| Burstable bandwidth | Extra bandwidth automatically added when traffic exceeds fixed bandwidth. Billed separately based on actual usage. |
| Per-node bandwidth cap | The maximum total bandwidth per single data node is 288 MB. This cap applies to fixed bandwidth and burstable bandwidth combined. |
Supported instances
Burstable bandwidth is available only for:
Cloud-native Redis Open-Source Edition
Tair (Enterprise Edition) memory-optimized instances
Tair (Enterprise Edition) persistent memory-optimized instances
Choose between burstable bandwidth and Bandwidth Auto Scaling
These two features are mutually exclusive — enable only one per instance.
| Feature | Best for | Scaling speed | Cost |
|---|---|---|---|
| Burstable bandwidth (this topic) | Unpredictable, instantaneous spikes lasting seconds or minutes. No threshold configuration required — the system scales based on real-time usage. | Seconds | 2.5x the price of Bandwidth Auto Scaling |
| [Bandwidth Auto Scaling](https://www.alibabacloud.com/help/en/redis/user-guide/enable-bandwidth-auto-scaling) | Predictable, periodic load changes lasting hours or longer. Requires bandwidth usage thresholds for scaling up and down. | Minutes | Lower. See Billing items. |
How it works
The system monitors inbound and outbound traffic in real time. When either direction exceeds the instance's fixed bandwidth, the system automatically increases bandwidth within seconds, up to the 288 MB per-node cap.
When the traffic spike ends and bandwidth usage drops below the fixed bandwidth level, the system releases the extra burstable bandwidth automatically.
For cluster or read/write splitting instances, the Bandwidth (MB/s) value on the Basic Information page shows the total bandwidth across all data nodes.
Billing
| Item | Details |
|---|---|
| Billable item | The burstable portion — bandwidth that exceeds the base bandwidth and fixed bandwidth. |
| Billing method | Billed hourly based on actual burst usage. |
| Unit price | 2.5x the price of a manual bandwidth upgrade. Prices vary by region. See Billing items. |
| Per-second cost formula | ⌊Accumulated burstable bandwidth⌋ × Hourly unit price ÷ 3600 |
| Settlement | At the end of each hour, the system totals per-second costs to generate the bill. |
Secondary nodes and read-only nodes receive the same bandwidth extension as the primary node and are not currently charged.
Billing example:
Assume an instance has a base bandwidth of 96 MB/s. For one hour during a day, service traffic peaks at 150 MB/s. For the remaining 23 hours, the traffic does not exceed the base bandwidth. The unit price for a fixed bandwidth extension in this region is CNY 0.017/MB/hour.
Plan | Description | Total cost for 24 hours |
Scenario 1: Enable both fixed bandwidth extension and burstable bandwidth | You purchase a 20 MB/s fixed bandwidth extension for a total fixed bandwidth of 116 MB/s. During the one-hour traffic peak, the excess 34 MB/s of traffic is handled by burstable bandwidth. For the remaining 23 hours, you are charged only for the fixed bandwidth extension. | (20 MB × CNY 0.017/MB + 34 MB × CNY 0.035/MB) × 1 hour + (20 MB × CNY 0.017/MB) × 23 hours = CNY 9.35 |
Scenario 2: Purchase only fixed bandwidth extension | To handle the 150 MB/s traffic peak, you purchase a 54 MB/s fixed bandwidth extension. This bandwidth is billed continuously for all 24 hours. Note Although this plan has the lowest unit price during traffic peaks, the fixed bandwidth is billed even when traffic is low. This results in the highest total cost and significant resource waste in scenarios with occasional traffic spikes. | (54 MB × CNY 0.017/MB) × 24 hours = CNY 22.03 |
Scenario 3: Enable only burstable bandwidth | You do not purchase any additional fixed bandwidth. The 54 MB/s of traffic that exceeds the base bandwidth is handled by burstable bandwidth and is billed only for the one-hour peak. Note This plan is ideal for handling unpredictable, instantaneous traffic spikes. You pay only for what you use, with no advance planning required. There are no extra costs after the traffic subsides, which results in the lowest total cost. | (54 MB × CNY 0.035/MB) × 1 hour = CNY 1.89 |
Enable burstable bandwidth
Log on to the console and go to the Instances page. In the top navigation bar, select the region where your instance resides, then click the instance ID.
In the Basic Information section, click Modify next to Bandwidth (MB/s).
In the panel that appears, turn on the Burstable Bandwidth switch.
The change takes effect in about one minute. Monitoring metrics may take 1–5 minutes to reflect the update. Enabling or disabling this feature does not interrupt instance access.
Monitor traffic
After enabling burstable bandwidth, monitor your instance's traffic usage to evaluate bandwidth requirements and cost-effectiveness. See View performance monitoring.