If your business experiences significant fluctuations with frequent peak periods, you can enable the IO performance burst feature for premium performance disks. This allows your disk IOPS to exceed the maximum IOPS limit, providing higher IO capabilities during business peaks to meet sudden business demands.
Background
Premium performance disk is a new storage type supported by RDS PostgreSQL. While maintaining compatibility with all features of ESSD disks, premium performance disks support the IO performance burst feature, which provides higher IOPS performance when storage capacity remains unchanged but IO pressure is high.
Feature introduction
After enabling IO performance burst for premium performance disks, the maximum IOPS and throughput limits of the instance will increase. Compared to instances without IO performance burst enabled, the differences are as follows:
When IO performance burst is enabled on the primary node, it is also enabled on the secondary node. Read-only instances do not automatically enable this feature. You need to enable it on the details page of the read-only instance.
Scenario | Maximum IOPS | Maximum throughput |
IO performance burst not enabled |
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IO performance burst enabled |
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If the throughput of an RDS instance reaches the upper limit, the IOPS of the instance is affected. If the IOPS of an RDS instance reaches the upper limit, the throughput of the instance is affected.
The above formulas do not apply to disk instances with general-purpose instance types because general-purpose instance types share resources and cannot guarantee maximum IOPS and maximum IO bandwidth.
For the maximum IOPS and maximum IO bandwidth of instance types in the above formulas, see RDS PostgreSQL primary instance type list.
The IOPS corresponding to the maximum IO bandwidth of instance type in the above formulas is calculated as:
maximum IO bandwidth of instance type(Gbit/s)×1024×1024÷8÷8, where the first 8 from left to right represents 1Byte=8bits, and the second 8 represents that each read/write operation in RDS PostgreSQL uses 8KB of data.
Scenarios
I/O loads increase due to heavy workloads, large transactions, full table scans, and queries that return a large amount of data. In some cases, the I/O usage may approach or reach 100% even if the CPU, memory, and storage resources are sufficient. In these scenarios, you must upgrade the instance specifications or storage type of your RDS instance. For example, you can upgrade the storage type from PL1 ESSD to PL2 ESSD.
If you do not upgrade the instance specifications or storage type, the I/O loads reach the upper limit. As a result, the instance performance decreases, queries time out, and connection errors occur.
If you upgrade instance specifications, the I/O performance can meet your business requirements, but the CPU, memory, and storage resources are idle and wasted.
If you upgrade the storage type, the I/O usage is increased within a short period of time, but storage resources are wasted and costs are increased when the I/O loads decrease.
The IO performance burst feature of premium performance disks can solve these problems. After enabling this feature, when IO load is high, IO performance burst is automatically triggered to increase the IO limit. When IO load decreases, the IO limit automatically returns to normal, achieving serverless IO performance and avoiding waste of IO performance and cost.
Feature benefits
Compared to upgrading instance specifications or storage levels, the IO performance burst feature of premium performance disks offers multiple advantages and can significantly reduce costs.
Charges are only applied to the IO performance burst volume.
IO performance burst volume is calculated by second.
Free quota is provided for IO performance burst volume, and only the volume exceeding the free quota will be charged.
Billing
The premium performance disk IO performance burst feature is currently part of a fee reduction campaign. Starting from June 20, 2024, the IO performance burst feature can be used free of charge. For more information, see Fee reduction announcement. After the campaign ends, billing will begin, but you will still enjoy a partial free quota, with only the excess being charged.
Billing method
Premium performance disk fee = Storage fee + IO performance burst fee
Storage fee: fees for the storage capacity that you purchase for your RDS instance. The subscription and pay-as-you-go billing methods are supported. The billing method is the same as ESSD PL1 disks. For more information, see Billable items.
IO performance burst fee:
Hourly IO performance burst fee for an instance = (Total IO performance burst volume of all instance nodes - Free quota) × IO performance burst unit priceNoteThe IO performance burst volume fee for RDS instances (including primary and secondary nodes) only supports pay-as-you-go billing. It is charged when IO performance burst is enabled and the IO performance burst volume exceeds the free quota.
Sum of IO performance burst volumes of all instance nodes
RDS edition
Instance IO performance burst volume
Basic Edition
Single node IO performance burst volume
High-availability Edition
Primary node IO performance burst volume + Secondary node IO performance burst volume
Cluster Edition
Primary node IO performance burst volume + All secondary nodes IO performance burst volume
NoteIf the I/O loads on the primary RDS instance is heavy and an I/O burst is triggered, an I/O burst is also triggered on the secondary RDS instance to ensure data and service consistency. The IO performance burst volume of the secondary node is basically the same as that of the primary node.
The IO performance burst feature for read-only instances needs to be enabled separately, with the same billing standard as the primary node. If the read-only instance is of the High-availability Edition, the fee includes the IO performance burst fees for both the primary and secondary nodes.
Free quota:
RDS provides a certain free usage quota for IO performance burst. When the used IO performance burst volume exceeds the free quota, RDS PostgreSQL charges a certain IO performance burst fee for different product editions.
Product edition
Free quota
Basic Edition
300,000 per hour
High-availability Edition
600,000 per hour
Cluster Edition
800,000 per hour
IO performance burst unit price: 0.0015 USD/10,000 IO
NoteIf the IO performance burst volume exceeding the free quota is less than 10,000, it is billed as 10,000.
Billing example
Example scenario | An RDS instance that runs RDS High-availability Edition and provides a storage capacity of 1,000 GB resides in the China (Beijing) region. The baseline IOPS is 50,000 and the number of burstable I/O operations per second is 20,000. The burst lasts for 40 seconds every hour throughout a month. |
The IO performance burst fee for this example scenario is calculated as follows: | |
IO performance burst volume | 800,000 per hour |
Free quota | 600,000 per hour |
Excess amount | 200,000 per hour |
Unit price | 0.0015 USD/10,000 IO |
Actual IO performance burst fee | 0.0015 × (80-60) × 24 × 30 = 21.6 USD |
The following table compares the fees of a general ESSD and a PL2 ESSD.
The prices in the following table are provided for reference only. The actual prices are displayed in the ApsaraDB RDS console.
Storage type | Storage unit price (USD/month) | Storage fee (USD) | IO performance burst fee (USD) | Total fee (USD/month) |
Premium performance disk | 244.8 | 244.8 × 1 = 244.8 | 21.6 | 244.8 + 21.6 = 266.4 |
ESSD PL2 disk | 489.6 | 489.6 × 1 = 489.6 | N/A | 489.6 |
Monthly savings of premium performance disk compared to ESSD PL2 disk: 489.6 - 266.4 = 223.2 USD
Within a certain time period, the shorter the high IO duration of the instance, the more cost-effective the premium performance disk is compared to the ESSD PL2 disk.
Enable or disable IO performance burst
Enabling or disabling the IO performance burst feature takes several minutes, depending on the instance usage (read and write traffic).
There is no transient connection during the process of enabling or disabling the IO performance burst feature, and it generally does not affect your business. In some cases, the IOPS of the RDS instance may fluctuate. We recommend that you perform this operation during off-peak hours.
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 ID of the instance.
In the Basic Information section, click Premium Performance Disk Switch Settings after Storage Type. In the dialog box that appears, turn on or off the IO Performance Burst switch.
References
For other storage types supported by RDS PostgreSQL, see Storage type introduction.
For more information about premium performance disks, see Premium performance disk.
When you need to address database disk IO performance bottlenecks, the Buffer Pool Extension (BPE) feature of premium performance disks can significantly improve database IO performance when facing large-scale or frequent data read/write requirements. For more information, see Buffer Pool Extension (BPE).
When you need to reduce storage costs, you can use the data archiving feature of premium performance disks to use Object Storage Service (OSS) as the storage medium for archiving cold data, significantly reducing storage costs. For more information, see Data archiving.
Related operations
API | Description |
When configuring the IO performance burst feature for premium performance disks:
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