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 the following storage types to suit different performance requirements of your workloads:

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

The supported IOPS depends on the I/O performance of the Elastic Volume Service (EVS) disk. For details, see the description about ultra-high I/O in Disk Types and Performance.
Extreme SSD
Uses 25GE network and RDMA technologies to provide you with up to 1,000 MiB/s throughput per disk and sub-millisecond latency.

The supported IOPS depends on the I/O performance of the EVS disk. For details, see the description about extreme SSDs in Disk Types and Performance.
Flexible SSD
Decouples capacity from performance and allows for tailored IOPS and throughput for your business requirements with fixed capacity. 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 disk 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 description about general-purpose SSD V2 in Disk Types and Performance.
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	128000
Maximum throughput	350 MiB/s	1000 MiB/s	1000 MiB/s
Read/write latency	1 ms	Sub-millisecond	Medium