Storage I/O performance

I/O size

I/O (Input/Output or Read/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 of Alibaba Cloud ECS provides isolation of storage I/O performance. Dedicated storage bandwidths are assigned to ECS instances and disks to avoid 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 ECS instances varies based on their instance families, instance types, and attached disks. The storage I/O performance of an instance is subject to the instance type. The higher specifications an instance type has, the higher storage I/O performance (IOPS and throughput) it provides.

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 total storage I/O performance of the disks.

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

When you understand the relationship between instance storage performance and disk storage performance, you can choose instance types and Elastic Block Storage devices based on their performance specifications. This prevents performance bottlenecks caused by improper configurations.

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

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