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
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 MariaDB, RDS for PostgreSQL and RDS for SQL Server 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, RDS for PostgreSQL, and RDS for SQL Server 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	1000 MB/s
Read/write latency	1 ms	Sub-millisecond