This topic provides an overview of primary ApsaraDB RDS instance types. This overview includes the most recent instance types, the earlier instance types, and the specifications for each instance type.

ApsaraDB RDS allows you to create read-only RDS instances, which are used to increase the read capability of your database system. For more information, see Overview of read-only ApsaraDB RDS for MySQL instances and Read-only ApsaraDB RDS instance types.

When you purchase a primary RDS instance, you must select a primary instance type. For more information, see Create an ApsaraDB RDS for MySQL instance.

Primary instance types for different database engines

Maximum IOPS for standard SSDs and ESSDs

The maximum IOPS of an RDS instance that is equipped with local SSDs varies based on the instance type. The maximum IOPS of an RDS instance that is equipped with standard SSDs or enhanced SSDs (ESSDs) varies based on the instance type and the storage capacity. The following table lists the formulas that are used to calculate the maximum IOPS of an RDS instance equipped with standard SSDs or ESSDs.

Note If the throughput of an RDS instance reaches the upper limit, the IOPS that the RDS instance can deliver is affected.
Storage type ESSD Standard SSD
PL PL3 PL2 PL1 None

Formula

(The storage capacity is measured in the unit of GB.)

min{1800 + 50 × Storage capacity, 1000000, Maximum IOPS for the instance type} min{1800 + 50 × Storage capacity, 100000, Maximum IOPS for the instance type} min{1800 + 50 × Storage capacity, 50000, Maximum IOPS for the instance type} min{1800 + 30 × Storage capacity, 25000, Maximum IOPS for the instance type}
The min{1800 + 50 × Storage capacity, 50000, Maximum IOPS for the instance type} formula is used as an example to describe the IOPS values in the preceding table.
  • min: specifies that the smallest IOPS among the three IOPS values in the formula is considered the maximum IOPS of the RDS instance.
  • 1800 + 50 × Storage capacity: the baseline IOPS that is supported by each ESSD of PL1.
  • 50000: the maximum IOPS that is supported by each ESSD of PL1. The maximum IOPS varies based on the storage type. For more information, see ESSDs.
  • Maximum IOPS for the instance type: the maximum IOPS that is supported by the instance type of the Elastic Compute Service (ECS) instance on which the RDS instance is deployed. For more information about the maximum IOPS for each instance type, see the specification tables that are provided in this topic.
The smallest IOPS among the three IOPS values in the applicable formula is considered the maximum IOPS of the RDS instance.
  • In the following examples, an RDS instance that is equipped with ESSDs of PL1 is used. The instance type is mysql.x2.large.2c, the maximum IOPS for the instance type is 20,000, and the storage capacity is 20 GB. In this example, the baseline IOPS is 2,800 based on the following calculation: 1800 + 50 × 20 = 2800. The smallest IOPS among the three IOPS values in the applicable formula is 2,800. Therefore, the maximum IOPS of the RDS instance is 2,800.
  • In the following examples, an RDS instance that is equipped with ESSDs of PL1 is used. The instance type is mysql.x2.large.2c, and the maximum IOPS for the instance type is 20,000. In this example, if the storage capacity of the RDS instance exceeds 6,000 GB, the baseline IOPS is 301,800. The smallest IOPS among the three IOPS values in the applicable formula is 20,000. Therefore, the maximum IOPS of the RDS instance is 20,000.
Note
  • If the maximum I/O bandwidth of the RDS instance is reached, the RDS instance may fail to deliver the maximum IOPS.
  • The baseline IOPS of an ECS cloud disk allows you to read and write 4 KB of data per second. The default IOPS that is supported by MySQL allows you to read and write 16 KB of data. Therefore, each read/write operation on MySQL consumes 4 IOPS.
  • In the specification tables that are provided in this topic, if the maximum IOPS and maximum I/O bandwidth Mbit/s for an instance type are marked as None, ApsaraDB RDS allows multiple instances of the instance type to preempt resources. In this case, the IOPS is not limited. The maximum I/O bandwidth is measured in the unit of Mbit/s.

Maximum throughput for standard SSDs and ESSDs

RDS instances that are equipped with standard SSDs or ESSDs are deployed on sixth-generation ECS instances. The maximum throughput of these RDS instances varies based on the instance type of the ECS instance on which these RDS instances are deployed. For more information, see Storage I/O performance of the new generation of enterprise-level instance families.

Note If the IOPS of an RDS instance reaches the upper limit, the throughput that the RDS instance can deliver is affected.
Storage type ESSD Standard SSD
PL PL3 PL2 PL1 None

Formula

(The throughput is measured in the unit of Mbit/s.)

min{120 + 0.5 × Storage capacity, 4000, Maximum I/O bandwidth for the instance type} min{120 + 0.5 × Storage capacity, 750, Maximum I/O bandwidth for the instance type} min{120 + 0.5 × Storage capacity, 350, Maximum I/O bandwidth for the instance type} min{120 + 0.5 × Storage capacity, 300, Maximum I/O bandwidth for the instance type}
The min{120 + 0.5 × Storage capacity, 350, Maximum I/O bandwidth for the instance type} formula is used as an example to describe the IOPS values in the preceding table.
  • 120 + 0.5 × Storage capacity: the baseline throughput that is supported by each ESSD of PL1.
  • 350: the maximum throughput that is supported by each ESSD of PL1. For more information about standard SSDs and ESSDs of various PLs, see ESSDs.
  • Maximum I/O bandwidth for the instance type: the maximum I/O bandwidth that is supported by the instance type of the ECS instance on which the RDS instance is deployed. For more information about the maximum I/O bandwidth for each instance type, see the specification tables that are provided in this topic.
    Note Only the maximum I/O bandwidths of ApsaraDB RDS for MySQL instances are provided in this topic.
The smallest throughput among the three throughput values in the applicable formula is considered the maximum throughput of the RDS instance.
  • In the following examples, an RDS instance that is equipped with ESSDs of PL3 is used. The instance type is mysql.x2.large.2c, the maximum I/O bandwidth is 1,536 Mbit/s, and the storage capacity is 20 GB. In this example, the baseline throughput is 130 Mbit/s, which is the smallest throughput among the three throughput values in the formula. Therefore, the maximum throughput of the RDS instance is 130 Mbit/s.
  • In the following examples, an RDS instance that is equipped with ESSDs of PL3 is used. The instance type is mysql.x2.large.2c, the maximum I/O bandwidth is 1,536 Mbit/s, and the storage capacity is 5,000 GB. In this example, the baseline throughput is 2,620 Mbit/s, which is higher than the maximum I/O bandwidth for the instance type. Therefore, the maximum throughput of the RDS instance is 1,536 Mbit/s.

Maximum number of connections and maximum IOPS for different instance configurations

The maximum number of connections and maximum IOPS of an RDS instance vary based on the instance configuration. For more information, see the following table. An RDS instance may fail to deliver the maximum number of connections or maximum IOPS due to various reasons.
Instance configuration Description Maximum number of connections guaranteed Maximum IOPS guaranteed
Dedicated RDS instance with standard SSDs or ESSDs A dedicated RDS instance that is equipped with standard SSDs or ESSDs exclusively occupies the allocated CPU, memory, storage, and I/O resources. Yes Yes
Dedicated host RDS instance A dedicated host RDS instance exclusively occupies the CPU, memory, storage, and I/O resources of the physical host on which the RDS instance is deployed. Yes Yes
Dedicated RDS instance with local SSDs A dedicated RDS instance that is equipped with local SSDs exclusively occupies the allocated CPU and memory resources, but shares I/O resources with the other RDS instances that are deployed on the same physical host. Yes No
General-purpose RDS instance A general-purpose RDS instance exclusively occupies the allocated memory resources, but shares CPU and I/O resources with the other RDS instances that are deployed on the same physical host. Yes No
Note For more information, see Instance families.

FAQ

  • When the same number of cores and the same size of memory capacity are provided, why does an entry-level RDS instance support a larger maximum number of connections and deliver higher IOPS than an enterprise-level RDS instance?

    An entry-level RDS instance belongs to the shared or general-purpose instance family, and an enterprise-level RDS instance belongs to the dedicated instance family. The shared and general-purpose instance families support the reuse of CPU resources. Therefore, an entry-level RDS instance supports a larger maximum number of connections and delivers higher IOPS than an enterprise-level RDS instance. The dedicated instance family supports the exclusive allocation of CPU and memory resources. Therefore, an enterprise-level RDS instance provides higher stability than an entry-level RDS instance. For more information, see Overview.

  • How do I query the available resources that I can purchase?

    You can call DescribeAvailableResource operation to query the available resources in a region.

  • Why are the queries per second (QPS) and the transactions per second (TPS) not provided?

    To obtain the QPS and TPS of an RDS instance, you must create objects on the RDS instance and perform tests. If the instance type remains unchanged, the QPS and TPS of an RDS instance vary based on the implementation method and the business system. For more information about how to perform tests and obtain the QPS and the TPS, see Test guidelines.