Enable I/O burst for ESSD AutoPL disks

If your application experiences spiky workloads with frequent traffic peaks, you can enable the I/O burst feature for your ESSD AutoPL disks. This feature boosts disk performance beyond the configured limit, providing the extra I/O capacity to handle traffic spikes. This topic describes how to enable and disable the I/O burst feature for the ESSD AutoPL disks of a PolarDB for MySQL cluster in the PolarDB console.

Prerequisites

Your PolarDB for MySQL cluster must use ESSD AutoPL disks.
The I/O burst feature is not supported for Serverless clusters.

Overview

When I/O burst is enabled for a disk, the maximum supported IOPS and throughput of the cluster increase. The following table compares the performance limits with and without I/O burst enabled.

Note

Enabling I/O burst on the primary node automatically enables it on all secondary nodes.

Scenario	Maximum IOPS	Maximum throughput
I/O burst disabled	The maximum IOPS of the cluster is 100,000 (the upper limit of baseline performance plus provisioned performance).	The maximum throughput of the cluster is 1,131 MB/s (the upper limit of baseline performance plus provisioned performance).
I/O burst enabled	The maximum IOPS of the cluster is 1,000,000.	The maximum throughput of the cluster is 4,096 MB/s (4 GB/s).

Note

Reaching the throughput limit can affect IOPS, and reaching the IOPS limit can affect throughput.
For more information about the maximum IOPS and I/O bandwidth, see Compute node specifications for x86 architecture and Compute node specifications for Yitian ARM architecture.
Use the following formula to calculate the IOPS at maximum I/O bandwidth:
- PolarDB engine version: PolarDB for MySQL Standard Edition.
- IOPS calculation: Maximum cluster I/O bandwidth (Gbit/s) × 1024 × 1024 ÷ 8 ÷ 16.
  Note: The number 8 converts bits to bytes (1 byte = 8 bits). The number 16 represents the data size of a single I/O operation in PolarDB for MySQL, which is 16 KB.

Impacts

Enabling or disabling I/O burst does not cause transient disconnections and generally has no impact on your services. In rare cases, the cluster's IOPS may fluctuate. Perform this operation during off-peak hours.

Notes

Enabling or disabling I/O burst takes several minutes. The exact duration depends on the cluster's read and write traffic.

Billing

The cost of an ESSD AutoPL disk includes three components: disk capacity cost, provisioned performance cost, and I/O burst cost.

Disk capacity cost: Billing for disk capacity starts when the disk is created. After creation, the disk provides the same baseline performance as an ESSD PL1 disk of the same capacity. For more information about billing rules, see Storage space billing rules.
Provisioned performance cost: This feature is billed on a Pay-As-You-Go basis after it is enabled.
I/O burst cost: This feature is billed on a Pay-As-You-Go basis after it is enabled.

Disk billing method

Disk cost (USD)

Disk performance

Subscription

Baseline performance: billed by storage space
Provisioned performance: Pay-As-You-Go
I/O burst: Pay-As-You-Go

Subscription duration: 1 month

Baseline performance cost: same as the price of an ESSD PL1 disk. For more information, see Storage space billing rules.
Provisioned performance costs vary by configuration:
Note
Cost formula: Unit price × Subscription duration.
- Single availability zone (hot standby storage disabled) provisioned performance cost:
  - USD 0.006912/IOPS/month.
- Two availability zones (hot standby storage enabled)
  - USD 0.011088/IOPS/month.
- Two availability zones (hot standby storage and hot standby compute cluster enabled)
  - USD 0.011088/IOPS/month.
- Three availability zones (hot standby storage and logger node enabled)
  - USD 0.011088/IOPS/month.
I/O burst cost:
- USD 0.02 per 10,000 I/Os.
- I/O burst cost formula: Burst I/O volume × Unit price.

IOPS:
- Baseline IOPS: max(min(1,800 + 50 × capacity, 50,000), 3,000)
- Total disk IOPS: baseline performance IOPS + provisioned performance
Throughput (MB/s):
- Baseline throughput: max(min(120 + 0.5 × capacity, 350), 125)
- Provisioned throughput: 16 KB × Provisioned IOPS/1,024
- Total disk throughput = Baseline throughput + Provisioned throughput

Pay-As-You-Go

Baseline performance: billed by storage space
Provisioned performance: Pay-As-You-Go
I/O burst: Pay-As-You-Go

Billing duration: 24 hours

Baseline performance cost: same as the price of an ESSD PL1 disk. For more information, see Storage space billing rules.
Provisioned performance costs vary by configuration:
Note
Cost formula: Unit price × Subscription duration.
- Single availability zone (hot standby storage disabled) provisioned performance cost:
  - USD 0.0000096/IOPS/hour.
- Two availability zones (hot standby storage enabled)
  - USD 0.0000154/IOPS/hour.
- Two availability zones (hot standby storage and hot standby compute cluster enabled)
  - USD 0.0000154/IOPS/hour.
- Three availability zones (hot standby storage and logger node enabled)
  - USD 0.0000154/IOPS/hour.
I/O burst cost:
- USD 0.02 per 10,000 I/Os.
- I/O burst cost formula: Burst I/O volume × Unit price.

Note

Usage for an ESSD AutoPL disk is based on its storage capacity and provisioned IOPS..
The I/O burst cost for a PolarDB cluster, including its primary and secondary nodes, is billed hourly on a Pay-As-You-Go basis. Usage of less than 10,000 I/Os in an hour is rounded up to 10,000.

Procedure

Enable I/O burst for a new cluster

Go to the PolarDB cluster purchase page.
During cluster configuration, set Storage Type to ESSD AutoPL, and then enable the I/O burst switch.

Modify I/O burst for an existing cluster

Log on to the PolarDB console, select the region where your cluster is located, and click the cluster ID.
In the Basic Information section, find the Distributed Storage subsection and click Change Storage Configuration.
On the Change Storage Configuration page, set Provisioned IOPS of AutoPL Disks as needed. In the Enable I/O Burst section, select Disable or Enable.
For Switching Time, select Switch Now or Switch At.
If you select Switch At, you can specify a time within the next 24 hours. The configuration change will be completed within 30 minutes after the scheduled time.
You can also view task details or cancel the task on the Scheduled Tasks page. For more information, see Scheduled tasks.
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