ApsaraDB RDS supports the following storage types: local SSD, standard SSD, and enhanced SSD (ESSD). This topic describes the differences between the three storage types and purchase suggestions.

Introduction

Storage type Description
ESSD
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 performance of ESSDs, see ESSDs.

Local SSD

Local SSDs reside on the same physical host as the database engine that is run by your RDS instance. You can store data in local SSDs to reduce I/O latencies.

Standard SSD
Standard SSDs are elastic block storage devices that are designed based on a distributed storage architecture. You can store data in standard SSDs to separate computing from storage.
Note Standard SSDs are being phased out. We recommend that you use ESSDs. For more information, see [Notice] End of sale for the standard SSD storage type for specific database engines in ApsaraDB RDS.

For more information about the differences in performance 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

Item ESSD Local SSD Standard SSD
I/O performance

★★★★★

Delivers higher I/O performance than standard SSDs.

★★★★★

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

★★★★

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

Configuration flexibility

★★★★★

Provides various configuration options and allows you to separately scale up the storage capacity. The storage capacity cannot be scaled down.

★★★★

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 scale up the storage capacity. The storage capacity cannot be scaled down.

Scalability

★★★★★

  • If your RDS instance runs MySQL, PostgreSQL, or MariaDB TX, you can upgrade the storage type of your RDS instance without the need to replicate data. You can scale up the storage capacity of your RDS instance within a few seconds.
  • If your RDS instance runs SQL Server, you can scale up the storage capacity of your RDS instance within a few minutes.

★★★

May require a few hours to copy data when you scale up the storage capacity of your RDS instance.

★★★★★

  • If your RDS instance runs MySQL, PostgreSQL, or MariaDB TX, you can upgrade the storage type of your RDS instance without the need to replicate data. You can scale up the storage capacity of your RDS instance within a few seconds.
  • If your RDS instance runs SQL Server, you can scale up the storage capacity of your RDS instance within a few minutes.
Impact of scale up
  • If your RDS instance runs MySQL, PostgreSQL, or MariaDB TX, no transient connections occur during the scale-up process.
  • If your RDS instance runs SQL Server, transient connections occur during the scale-up process.
Transient connections occur during the scale-up process.
  • If your RDS instance runs MySQL, PostgreSQL, or MariaDB TX, no transient connections occur during the scale-up process.
  • If your RDS instance runs SQL Server, transient connections occur during the scale-up process.

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