ApsaraDB for MongoDB:Instance types

Due to the updates of physical resources, since July 10, 2017, the following types of ApsaraDB for MongoDB instances are used.

• Standalone instance types

• Replica set instance types

• Sharded cluster instance types

The IOPS of an ESSD is calculated based on the following formula:

min {1,800 + 50 × Storage capacity, 50000, ECS-limited IOPS}

Description of the values in the preceding formula:

• 1,800 + 50 × Storage capacity: the basic calculation formula for the IOPS of the ESSD.

• 50,000: the maximum IOPS of a single PL1 ESSD. For more information, see ESSDs.

• ECS-limited IOPS: the maximum IOPS of the ECS instance type. For the maximum IOPS of each instance type, see the New Instance types section in this topic.

The actual IOPS of an instance is the minimum of the three values. Examples:

• The storage capacity of an instance is 20 GB. The actual IOPS of the instance is 2,800 (1,800 + 50 × 20).

• If the instance type is mdb.shard.2x.xlarge.d, the ECS-limited IOPS is 21,000. If the storage capacity of the instance is 6,000 GB, the calculated IOPS of the instance is 301,800, which exceeds the maximum IOPS of a single PL1 ESSD and the ECS-limited IOPS. In this case, the actual IOPS of the instance is 21,000.

The maximum number of connections and maximum IOPS of an instance vary based on the instance category. In practice, an instance may fail to deliver the maximum number of connections or maximum IOPS due to various reasons. The following list describes the instance categories.