ApsaraDB RDS supports local SSDs, standard SSDs, and enhanced SSDs (ESSDs). These storage types meet the reliability, durability, and read and write performance requirements that are specified in the ApsaraDB RDS service level agreement (SLA).

Introduction

ApsaraDB RDS provides these storage types to meet your business requirements in various scenarios.

  • Local SSDs

    Local SSDs are a recommended type of storage medium. Local SSDs reside on the same physical host as the database engine that is used. You can store data on local SSDs to reduce I/O latencies.

  • Standard SSDs
    Standard SSDs are elastic block storage devices that are designed based on a distributed storage architecture. You can store data on standard SSDs to separate computing from storage.
    Note Standard SSDs are being phased out. We recommend that you use ESSDs.
  • ESSDs
    ESSDs are also a recommended type of storage medium. ESSDs are developed by Alibaba Cloud based on the next-generation distributed block storage architecture. ESSDs deliver ultra high storage performance. ESSDs are integrated with 25 Gigabit Ethernet and remote direct memory access (RDMA) technologies. ESSDs can help you reduce one-way latencies and process up to 1 million read and write requests at random per second. ESSDs are provided in three performance levels (PLs) as indicated on the ApsaraDB RDS buy page:
    • ESSD PL1: This is the most basic PL of ESSDs.
    • ESSD PL2: An ESSD of PL2 delivers IOPS and throughput that are approximately two times the IOPS and throughput delivered by an ESSD of PL1.
    • ESSD PL3: An ESSD of PL3 delivers IOPS that is up to 20 times the IOPS delivered by an ESSD of PL1. An ESSD of PL3 also delivers throughput that is up to 11 times the throughput delivered by an ESSD of PL1. ESSDs of PL3 are suitable for business scenarios in which highly concurrent requests must be processed with high I/O performance and at low read and write latencies.

For more information about the differences in performance and use scenarios among the preceding storage types, see EBS performance. The performance comparison items include the maximum capacity per disk, maximum IOPS, and maximum throughput.

Note All of the preceding storage types meet the reliability, durability, and read and write performance requirements that are specified in the ApsaraDB RDS SLA.
  • Local SSDs are suitable for RDS High-availability Edition, which provides one primary RDS instance and one secondary RDS instance. Local SSDs are also suitable for RDS Enterprise Edition, which provides one primary RDS instance, one secondary RDS instance, and one logger RDS instance. Both RDS editions support failovers. If the primary RDS instance is faulty, your database system can fail over to the secondary RDS instance within a few seconds.
  • Standard SSDs and ESSDs both use a distributed storage architecture. This architecture supports multiple data copies, which are used to ensure data reliability. If you use RDS Basic Edition, the recovery from a fault requires a long period of time. If you use RDS High-availability Edition, RDS Cluster Edition, or RDS Enterprise Edition, your database system can fail over to the secondary RDS instance within a few seconds in the event of a fault.

View the storage type of an RDS instance

Log on to the ApsaraDB RDS console and go to the Basic Information page of the RDS instance. In the Basic Information section of the page, view the storage type of the RDS instance.

New ApsaraDB RDS console

Comparison between storage types

Table 1. Functionality comparison
Item Local SSD Standard SSD ESSD (recommended)
I/O performance

★★★★★

Helps reduce I/O latencies and improve I/O performance.

★★★★

Requires additional network I/O overheads, which decrease I/O performance.

★★★★★

Delivers higher I/O performance than standard SSDs.

Configuration flexibility

★★★★

Provides various configuration options and allows you to separately adjust the storage capacity. Some instance types provide a fixed amount of storage capacity when used with local SSDs.

★★★★★

Provides various configuration options and allows you to separately increase the storage capacity.

★★★★★

Provides various configuration options and allows you to separately increase the storage capacity.

Scalability

★★★

May require a few hours to copy data when you scale the database system.

★★★★★

Allows you to scale the database system within a few minutes.

★★★★★

Allows you to scale the database system within a few minutes.

Product support

For more information about the storage types and the features that are supported by different database engines, see the following topics:

FAQ

FAQ about storage capacity