Storage I/O performance

I/O size

I/O (Input/Output or Reads/Write) is random or sequential data requests initiated by an application. The volume of I/O requests is also known as the I/O size in KiB, such as 4 KiB, 256 KiB, and 1,024 KiB.

Storage I/O performance of instances

The new generation of enterprise-level instance families for Alibaba Cloud elastic compute features storage I/O performance isolation. Dedicated storage bandwidths are assigned to ECS instances and disks to avoid the storage I/O preemption among ECS instances. The new generation of enterprise-level instance families ensures consistent storage I/O performance of applications even during peak hours.

Relationship between instance types and storage I/O performance

The storage I/O performance of an ECS instance varies with instance families and disk-attached instance types. The storage I/O performance of an instance subjects to the instance type. A higher instance type provides higher storage I/O performance (IOPS and throughput).

After you create an ECS instance and attach disks to it, the final storage I/O performance of the ECS instance is determined as described in the following section:

• Scenario 1: If the total storage performance of the attached disks exceeds the maximum storage I/O performance that the instance type can deliver, the final storage I/O performance of the instance is limited to the maximum storage I/O performance of that instance type.
• Scenario 2: If the total storage performance of the attached disks does not exceed the maximum storage I/O performance that the instance type can deliver, the final storage I/O performance of the instance is limited to the maximum storage I/O performance of the disks.

For example, the ecs.g6.8xlarge instance type features 60,000 IOPS. If a 1,600 GiB ESSD PL2 is attached to an instance of the instance type and the IOPS of the ESSD PL2 is 81,800, the maximum storage IOPS of the instance is 60,000 instead of 81,800. For information about the performance levels of ESSDs, see Enhanced SSDs.

After you understand the relationship between instance storage performance and disk storage performance, you can choose instance types and Block Storage devices based on the performance data of instances and disks that meet your business needs. This prevents performance bottlenecks caused by using improper configurations.

Storage I/O performance of new generation of enterprise-level instance families

The following table lists the storage I/O performance of the new generation of enterprise-level instance families. For information about other metrics of the instance families, see Instance families.