This topic describes the current and legacy instance specifications for ApsaraDB for MongoDB.
New instance types
Due to hardware upgrades, ApsaraDB for MongoDB instances created or reconfigured on or after July 10, 2017, use the following specifications.
The memory specified for an instance includes memory used by MongoDB management services, database services, and the underlying operating system. This includes memory reserved for the BIOS, kernel, and hypervisor. As a result, the available memory is less than the amount listed in the specifications.
Serverless instances support read/write capacity from 100 to 8,000 CUs in increments of 100 CUs. Storage space ranges from 1 GB to 100 GB in increments of 1 GB.
Legacy instance specifications
For information about legacy ApsaraDB for MongoDB instance specifications, see Legacy specifications.
About cloud disk IOPS
For local SSDs, the input/output operations per second (IOPS) limit is fixed based on the instance type. For ESSD cloud disks, the IOPS is proportional to the storage space. The ECS instance type also imposes a maximum IOPS limit on the ESSD.
The formula to calculate the IOPS for an ESSD cloud disk is as follows:
min{1800 + 50 * storage_space, 50000, ecs_iops_limit}If throughput reaches its limit, IOPS is also affected. For more information, see Storage I/O performance of new-generation enterprise-level instance families.
The values in the formula are described as follows:
1800 + 50 * storage_space: The basic formula to calculate the IOPS of an ESSD cloud disk.50000: The maximum IOPS for a single disk at ESSD performance level (PL) 1. For more information, see ESSD cloud disks.ecs_iops_limit: The maximum IOPS limited by the ECS instance type.
The IOPS of an instance is the minimum of the three values in the formula. For example:
An instance has 20 GB of storage space. Using the formula 1800 + 50 × 20, the result is 2,800. The IOPS for this instance is 2,800.
An instance of the
mdb.shard.2x.xlarge.dtype has a maximum IOPS limit of 20,000. If this instance has 6,000 GB of storage space, the formula result is 301,800. This value exceeds the maximum limits of the ECS instance type and PL1. Therefore, the IOPS for the instance is 20,000.
In practice, the maximum IOPS of an instance that uses cloud disks is greater than or equal to the value calculated by this formula.
About cloud disk throughput
For enterprise SSDs, the maximum throughput is limited by their specifications, storage capacity, and the ECS instance type.
The formula to calculate the throughput for an ESSD cloud disk is as follows:
min{120 + 0.5 * storage_space, 350, ecs_throughput_limit}If IOPS reaches its limit, throughput is also affected. For more information, see Storage I/O performance of new-generation enterprise-level instance families.
The values in the formula are described as follows:
120 + 0.5 * storage_space: The formula to calculate the throughput of an ESSD cloud disk, in MB/s.350: The maximum throughput for a single disk at ESSD performance level (PL) 1. For more information, see ESSD cloud disks.ecs_throughput_limit: The maximum I/O bandwidth limited by the ECS instance type.
The throughput of an instance is the minimum of the three values in the formula. For example:
An instance has 20 GB of storage space. Using the formula 120 + 0.5 × 20, the result is 130. The throughput for this instance is 130 MB/s.
An instance of the
mdb.shard.2x.xlarge.dtype has a maximum throughput limit of 192 MB/s. If this instance has 6,000 GB of storage space, the formula result is 3,120 MB/s. This value exceeds the maximum limits of the ECS instance type and PL1. Therefore, the throughput for the instance is 192 MB/s.
In practice, the maximum throughput of an instance that uses cloud disks is greater than or equal to the value calculated by this formula.
Specification type descriptions
The maximum connections and maximum IOPS listed in the specification tables may not be reached in practice. The actual values depend on the instance specification type. The following table describes each specification type.
Specification type | Description | Guaranteed maximum connections | Guaranteed maximum IOPS |
Cloud Disk Dedicated Edition | Exclusively uses CPU, memory, storage medium, and I/O resources. | Yes | Yes |
Dedicated physical machine | Exclusively uses CPU, memory, storage medium, and I/O resources. | Yes | Yes |
Dedicated with local disks | Exclusively uses CPU and memory. Shares I/O resources with other users on the same physical machine. | Yes | No |
General-purpose | Exclusively uses memory. Shares CPU and I/O resources with other users on the same physical machine. | Yes | No |
For more information, see Instance families.