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.

Performance Comparison

**Table 1** Performance comparison
Item	Cloud SSD	Extreme SSD
I/O performance	Subpar 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	Medium	Medium