If your workload fluctuates or experiences frequent traffic peaks, you can enable the I/O performance bursting feature for your high-performance cloud disk. This feature allows your cloud disk's IOPS to exceed the standard maximum, providing higher I/O capacity to handle sudden business demands during peak times.
Overview
After you enable I/O performance bursting for a high-performance cloud disk, the maximum IOPS and throughput limits for the instance increase. The following table compares the performance with and without this feature enabled.
When you enable I/O performance bursting on the primary node, the feature is also automatically enabled on the secondary node. However, it is not automatically enabled on read-only instances. You must enable it separately on the details page of each read-only instance.
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Scenario |
Maximum IOPS |
Maximum throughput |
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I/O performance bursting disabled |
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I/O performance bursting enabled |
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When throughput reaches its limit, it can affect IOPS. Similarly, when IOPS reaches its limit, it can affect throughput.
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The formula above does not apply to cloud disk instances of general-purpose instance types because they share resources and cannot guarantee maximum IOPS and maximum I/O bandwidth.
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You can calculate the IOPS that corresponds to the maximum I/O bandwidth of the instance type as follows:
Maximum I/O bandwidth of the instance type (Gbit/s) * 1024 * 1024 / 8 / 8. In this formula, the first 8 indicates that 1 byte = 8 bits, and the second 8 indicates that ApsaraDB RDS for SQL Server uses a data block size of 8 KB for a single read/write operation.
Use cases
High-performance cloud disks are suitable for scenarios with high or fluctuating I/O workloads.
Workload peaks, large transactions, full table scans, and queries that return large amounts of data can cause the I/O load to increase. In some cases, your CPU, memory, and storage space may be sufficient, but I/O utilization is approaching or has reached 100%. In this situation, you would typically need to upgrade the instance configuration or storage level (for example, from PL1 to PL2).
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If you do not upgrade, an I/O load that exceeds the instance's I/O limit can cause performance degradation, query timeouts, and even connection exceptions.
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If you upgrade the instance configuration to meet I/O performance needs, this may result in idle and wasted CPU, memory, and storage resources.
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If you upgrade the storage level, you can fully utilize I/O performance in the short term, but this wastes resources and money when the I/O load decreases.
The I/O performance bursting feature of high-performance cloud disks solves these problems. When this feature is enabled, I/O performance bursting is automatically triggered during high I/O loads to increase the I/O limit. When the I/O load drops, the limit automatically returns to the baseline. This provides a Serverless I/O performance model that helps you avoid wasting I/O resources and costs.
Benefits
The I/O performance bursting feature is more cost-effective than upgrading the instance configuration or storage level.
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You are billed only for the burst I/O usage.
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Burst I/O usage is calculated by the second.
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The feature includes a free quota for I/O performance bursting. You are charged only for usage that exceeds this free quota.
Prerequisites
Your ApsaraDB RDS for SQL Server instance must meet the following requirements:
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Storage type: high-performance cloud disk
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Instance billing method: subscription or pay-as-you-go (not supported for Serverless instances)
To change the storage type of an instance, see Change ESSD to a high-performance cloud disk.
Impacts
Enabling or disabling the I/O performance bursting feature does not cause a transient disconnection and typically does not affect your services. However, in rare cases, instance IOPS may fluctuate. Therefore, we recommend that you perform this operation during off-peak hours.
Usage notes
Enabling or disabling I/O performance bursting takes several minutes. The exact duration depends on the instance's usage, such as read and write traffic.
Billing
The I/O performance bursting feature for high-performance cloud disks is subject to a promotional fee waiver. Starting from April 16, 2024, the feature is free to use. When the promotion ends, billing will commence. You will still receive a free quota, and you are charged only for usage that exceeds it. The billing standards are as follows:
Enable or disable I/O performance bursting
Log on to the ApsaraDB RDS console and go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the instance ID.
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In the Basic Information section, you can find the switch to enable or disable I/O performance bursting.
Click High-performance Cloud Disk Switch Settings to the right of High-performance Cloud Disk. In the dialog box that appears, turn the I/O performance bursting switch on or off.
Related documents
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For information about other storage types supported by ApsaraDB RDS for SQL Server, see Storage types.
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If you face high storage pressure and want to reduce storage costs, use the database-level Archive Data to OSS feature for ApsaraDB RDS for SQL Server.