Help Center/ Relational Database Service/ User Guide (Ally Region)/ Service Overview/ DB Instance Description/ DB Instance Storage Types
Updated on 2026-04-24 GMT+08:00
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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 storage types to suit different performance requirements of your workloads.

  • Cloud SSD or Ultra-high I/O

    Cloud SSDs and Ultra-high I/O drives are both cloud drives used to decouple storage from 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.
    • For RDS for PostgreSQL instances, this storage type is displayed as Cloud SSD.
  • 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.

    • Only RDS for MySQL and RDS for PostgreSQL support extreme SSDs.

Performance Comparison

Table 1 Performance comparison

Item

Cloud SSD

Extreme SSD

I/O performance

Sub-par I/O performance due to additional network I/O overheads

Higher I/O performance than cloud SSDs

Elastic scalability

Scaling in seconds

Scaling in seconds

Maximum IOPS

50,000

128,000

Maximum throughput

350 MB/s

1,000 MB/s

Read/write latency

1 ms

Sub-millisecond
Parent topic: DB Instance Description