ApsaraDB RDS for MySQL storage types: Differences and selection - ApsaraDB RDS

Storage type introduction

Type	Description
local SSD	This local attachment provides high read/write I/O and extremely low latency because data is stored and accessed on the same machine. A local SSD can deliver up to 150,000 IOPS with latency in the microsecond range. It offers up to 16 TB of storage space and improves backup and recovery speeds by up to 10 times compared to self-managed databases. This storage type is suitable for I/O-intensive applications and scenarios with high-concurrency reads and writes, such as e-commerce flash sales and high-frequency trading systems.
General ESSD	General ESSD is compatible with all features of ESSDs and provides the following additional capabilities: I/O burst: Allows the IOPS of a cloud disk to exceed its defined maximum to provide higher I/O capacity for business peaks and bursty workloads. Buffer Pool Extension (BPE): Expands the buffer pool to improve disk I/O efficiency and system response speed. This feature accelerates caching and enhances read/write performance of the RDS instance. data archiving: Moves infrequently accessed data to Object Storage Service (OSS). This can reduce storage costs by up to 80% compared to ESSD PL1. It is ideal for instances that contain tables that are rarely accessed or modified. storage compression: Compresses user data at the storage layer, including both actual data and system logs, to reduce the storage cost per unit of data.
ESSD	Enhanced SSDs (ESSDs) are a new generation of ultra-high-performance cloud disks from Alibaba Cloud. Based on a next-generation distributed block storage architecture and integrated with 25GE networking and RDMA technology, an ESSD provides up to 1 million random read/write IOPS per disk and lower latency than a standard SSD. ESSDs are available in the following performance levels (PLs): ESSD PL1:An ESSD at performance level PL1. ESSD PL2: Delivers approximately twice the IOPS and throughput of an ESSD at PL1. ESSD PL3: Delivers up to 20 times the IOPS and 11 times the throughput of an ESSD at PL1. It is suitable for business scenarios that require extremely high concurrent I/O performance and stable, low read/write latency. For more information about the performance of ESSDs, see ESSDs.
standard SSD	A standard SSD is an elastic block storage device based on a distributed storage architecture. It separates compute from storage. Note Standard SSDs are being phased out. We recommend that you use ESSDs. For more information, see [EOS/Discontinuation] End of sale for the standard SSD storage type for specific database engines in ApsaraDB RDS from July 01, 2022.

For a performance comparison among storage types, including capacity per disk, maximum IOPS, and maximum throughput, see Block storage performance.

Note

All of these storage types meet the reliability, durability, and read/write performance commitments specified in the product SLA.

local SSD: Used by RDS instances that run RDS High-availability Edition. This edition uses a primary/secondary architecture. If the primary node fails, a primary/secondary switchover completes within seconds.
cloud disk (standard SSD, ESSD, and General ESSD): This distributed storage uses multi-replica redundancy to ensure data reliability. If the RDS instance runs RDS High-availability Edition or RDS Cluster Edition, it supports automatic switchovers within seconds.

View storage type

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

Storage type comparison

Note

Currently, only ApsaraDB RDS for MySQL instances that run RDS High-availability Edition support local SSDs.

Item	local SSD	General ESSD	ESSD
I/O performance	★★★★★ Low latency and high performance: IOPS: Determined by the instance specification. I/O latency: 10 to 50 microseconds	★★★★★★ Provides the Buffer Pool Extension (BPE), I/O burst, and data archiving features. I/O performance is as follows: IOPS: Determined by both the disk and instance specifications. I/O latency: 100 to 200 microseconds	★★★★★ Significant improvement over standard SSDs: IOPS: Determined by both the disk and instance specifications. I/O latency: 100 to 200 microseconds
Configuration flexibility	★★★★ Offers flexible configuration options, and storage capacity can be adjusted separately. However, for some instances that use local SSDs, the storage capacity is tied to the instance specification and cannot be adjusted independently.	★★★★★ Multiple configuration options are available. Supports scaling storage capacity up or down. Note You can reduce the storage capacity only for eligible MySQL instances. For more information, see Configuration items and Change instance specifications.	★★★★★ Multiple configuration options are available. Supports scaling storage capacity up or down. Note You can reduce the storage capacity only for eligible MySQL instances. For more information, see Configuration items and Change instance specifications.
Backup method	Physical backup using XtraBackup	ESSD snapshot backup	ESSD snapshot backup
Speed of backup, read-only instance creation, and instance cloning	★★★ Varies by disk size and takes hours.	★★★★★ Takes a few seconds.	★★★★★ Takes a few seconds.
Time required for capacity scaling	★★★★ Requires data to be copied, taking several hours.	★★★★★ Supports online scaling, which completes in seconds.	★★★★★ Supports online scaling, which completes in seconds.
Impact of capacity scaling	Causes a brief connection interruption.	No impact.	No impact.
Data durability	★★★★ In rare cases, hardware failures can cause data corruption. A secondary node is required for data protection. RDS High-availability Edition instances that use local SSDs offer an SLA of 99.995%.	★★★★★ Delivers 99.9999999% data durability. Supports single-node RDS Basic Edition deployments to reduce costs.	★★★★★ Delivers 99.9999999% data durability. Supports single-node RDS Basic Edition deployments to reduce costs.

Selection recommendations

Prioritize General ESSDs. Consider the following scenarios:

For I/O-intensive workloads, enable the Buffer Pool Extension (BPE) feature.
For I/O workloads that fluctuate significantly, enable the I/O burst feature.
If your database has many infrequently accessed or modified tables, enable the data archiving feature.

If you explicitly require a high performance level (PL), choose an ESSD.

Feature support

For information about the storage types and features supported by each instance type, see ApsaraDB RDS for MySQL features.

FAQ

FAQ about storage capacity