Updated on 2025-09-17 GMT+08:00

DB Instance Storage Types

The database system is generally an important part of an IT system and has high requirements on storage I/O performance. You can select a storage type based on service demands. You cannot change the storage type after the DB instance is created.

Description

RDS supports Cloud SSD (also called Ultra-high I/O) and Extreme SSD to suit different performance requirements of your workloads.

  • Cloud SSD or Ultra-high I/O

    Stores data in cloud disks for decoupled storage and compute. The maximum throughput is 350 MB/s.

    • For RDS for MySQL instances, this storage type is normally displayed as Cloud SSD, but for existing instances in certain regions it is displayed as Ultra-high I/O.
    • The supported IOPS depends on the I/O performance of the Elastic Volume Service (EVS) disk. For details, see "Ultra-high I/O" in Disk Types and Performance of the Elastic Volume Service Service Overview.
  • Extreme SSD

    Uses 25GE network and RDMA technologies to provide you with up to 1,000 MB/s throughput per disk and sub-millisecond latency.

    • The supported IOPS depends on the I/O performance of the EVS disk. For details, see "Extreme SSD" in Disk Types and Performance of the Elastic Volume Service Service Overview.
  • Flexible SSD

    Decouples capacity from performance and allows for tailored IOPS and throughput for your business requirements. This storage type is ideal for mainstream interactive applications that require high performance and low latency.

    • You can preconfigure an IOPS ranging from 3,000 to 128,000. This IOPS must also be less than or equal to 500 times the capacity. You can preconfigure a throughput ranging from 125 to 1,000 MiB/s. This throughput must also be less than or equal to the IOPS divided by 4. For details, see the descriptions of "General Purpose SSD V2" in Disk Types and Performance in the Elastic Volume Service Service Overview.

    To purchase instances with Flexible SSDs, submit a service ticket.

Performance Comparison

Table 1 Performance comparison

Item

Cloud SSD

Extreme SSD

Flexible SSD

I/O performance

Subpar I/O performance due to additional network I/O overheads

Higher I/O performance than cloud SSDs

On-demand IOPS and throughput

Elastic scalability

Scaling in seconds

Scaling in seconds

Scaling in seconds

Maximum IOPS

50,000

128,000

128,000

Maximum throughput

350 MiB/s

1,000 MiB/s

1,000 MiB/s

Read/write latency

Medium

Medium

Medium