Differences between ApsaraDB RDS storage types and selection guide - ApsaraDB RDS

ApsaraDB RDS provides the following data storage types: Enhanced SSDs (ESSDs), Premium Local SSDs, standard SSDs, and Premium ESSDs. This topic describes these storage types, compares their differences, and provides selection guidelines.

Introduction to storage types

Storage type	Description	Supported engines
ESSD	Enhanced SSD (ESSD) is a new ultra-high performance cloud disk product from Alibaba Cloud. Based on a new-generation distributed block storage architecture, ESSDs use 25GE networks and Remote Direct Memory Access (RDMA) technology. They provide up to 1 million random read/write input/output operations per second (IOPS) for a single disk and lower one-way latency than standard SSDs. ESSDs are available in the following categories: PL1 ESSD: An ESSD with PL1. PL2 ESSD: Compared to PL1, a PL2 ESSD increases IOPS and throughput by about two times. PL3 ESSD: Compared to PL1, a PL3 ESSD increases IOPS by up to 20 times and throughput by up to 11 times. It is suitable for business scenarios that require extremely high concurrent I/O performance and stable read/write latency. For more information about the performance of ESSDs, see ESSDs.	MySQL, PostgreSQL, SQL Server, and MariaDB
Premium Local SSD	A Premium Local SSD is a proprietary intelligent local disk developed by ApsaraDB RDS. It is located on the same physical server as the MySQL database. Data storage and read/write operations are completed locally, which provides high read/write I/O and low latency. A Premium Local SSD provides up to 150,000 IOPS, I/O latency as low as microseconds, and up to 16 TB of disk space. Its backup and restore speed is 10 times faster than self-managed databases. It is suitable for I/O-intensive applications or scenarios with high concurrency for read and write operations, such as flash sales and high-frequency trading systems.	MySQL
Premium ESSD	Premium ESSDs are compatible with all the attributes of enterprise SSDs, and they also provide additional features such as I/O performance burst, Buffer Pool Extension (BPE), and data archiving. Performance burst (supported by MySQL and PostgreSQL): Allows the IOPS of a cloud disk to exceed its maximum limit. This provides higher I/O capabilities during business peaks to meet bursty business requirements. Buffer Pool Extension (BPE) (supported by MySQL and PostgreSQL): Helps expand the size of the buffer pool, improve disk I/O efficiency and system response speed, and accelerate caching. This improves the overall read and write performance of the RDS instance. Data archiving (supported by MySQL and PostgreSQL): Moves infrequently accessed data to Object Storage Service (OSS). This reduces data storage costs by 80% compared to PL1 ESSDs. This feature is suitable for instances that contain tables that are not frequently accessed or modified. For more information, see Premium ESSDs for ApsaraDB RDS for MySQL, Premium ESSDs for ApsaraDB RDS for PostgreSQL.	MySQL and PostgreSQL
Standard SSD	A standard SSD is an Elastic Block Storage device based on a distributed storage architecture that decouples compute and storage. Note Standard SSDs are being phased out. We recommend that you use ESSDs. For more information, see [End of Sale/End of Life] Starting from July 1, 2022, standard SSDs are no longer available for purchase for some RDS instances.	MySQL, PostgreSQL, SQL Server, and MariaDB

For a performance comparison between storage types, including single-disk capacity, maximum IOPS, and maximum throughput, see Block storage performance.

Note

The reliability, durability, and read and write performance of these storage types meet the commitments in the Service-Level Agreement (SLA).

Premium Local SSDs: The RDS instances that use Premium Local SSDs have a high-availability series architecture with primary and secondary nodes. If the primary node fails, an automatic switchover to the secondary node is completed within seconds.
Cloud disks (standard SSDs, ESSDs, and Premium ESSDs): These are distributed cloud disks that use multiple replicas to ensure data reliability. If the associated RDS instance is a high-availability series or Cluster Edition instance, it supports automatic switchover within seconds.

View the storage type

You can view the storage type of an instance on the Basic Information page.

Differences between storage types

Note

Currently, only ApsaraDB RDS for MySQL high-availability series instances support Premium Local SSDs.

Item	Enterprise SSD	Premium ESSD	Premium Local SSD
I/O performance Note The speed and efficiency of a disk when processing data read and write requests. This includes IOPS, throughput, and access latency.	★★★★★ A significant improvement over standard SSDs: IOPS: Determined by both disk specifications and instance type. I/O latency: 100 to 200 microseconds.	★★★★★★ Built on ESSDs, with the addition of the performance burst, Buffer Pool Extension (BPE), and data archiving features. I/O performance is as follows: IOPS: Determined by both disk specifications and instance type. I/O latency: 100 to 200 microseconds.	★★★★★ Low I/O latency and high performance: IOPS: Determined by the instance type. I/O latency: 10 to 50 microseconds.
Flexibility of specifications	★★★★★ Many configurations are available. Supports scaling out or scaling in disk space. Note Scaling in is supported only for certain MySQL and PostgreSQL instances under specific conditions. For more information, see Overview of instance configuration changes and Change configuration.	★★★★★ Many configurations are available. Supports scaling out or scaling in disk space. Note Scaling in is supported only for certain MySQL and PostgreSQL instances under specific conditions. For more information, see Overview of instance configuration changes and Change configuration.	★★★★ Many configurations are available. You can adjust the disk space separately. For some instances with Premium Local SSDs, the disk space is tied to the instance type and cannot be adjusted separately.
Backup method	ESSD snapshot backup.	ESSD snapshot backup.	XtraBackup physical backup.
Speed of backup, read-only instance creation, and instance cloning	★★★★★ Operations are completed in seconds.	★★★★★ Operations are completed in seconds.	★★★ The duration is related to the disk size and can take hours.
Scale-out duration	★★★★★ Online upgrade. Scaling out is completed in seconds.	★★★★★ Online upgrade. Scaling out is completed in seconds.	★★★★ Data must be copied. This may take several hours.
Impact of scaling out	No impact.	No impact.	A transient disconnection occurs.
Data durability	★★★★★ Data reliability is 99.9999999%. Supports single-node Basic Edition instances to reduce costs.	★★★★★ Data reliability is 99.9999999%. Supports single-node Basic Edition instances to reduce costs.	★★★★ A hardware failure may cause data corruption. A secondary database is required to ensure data availability. The SLA for high-availability series instances with local disks is 99.995%.

Selection guide

We recommend using enterprise SSDs.

Product support

For information about the storage types and features supported by each instance type, see:

FAQ

FAQ about disk space