Help Center/ Document Database Service/ Service Overview/ Instances/ Instance Specifications/ Replica Set
Updated on 2026-08-17 GMT+08:00
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Replica Set

Instances of the same type have different memory specifications. You can select instances of different specifications based on application scenarios.

This section describes replica set instance specifications. The instance specifications depend on the selected CPU model.

The default maximum number of connections has been adjusted. Query the number of connections based on the instance's creation time. For details about the number of connections for instances created before July 2021, see Historical Instance Specifications.

Instance Specifications

DDS replica set instances have two specification types: general-purpose and enhanced II. For details, see Table 1.

Table 1 Specification type

Specification Type

Description

Application Scenario

General-purpose

CPU resources are shared with other general-purpose DB instances on the same physical machine. CPU usage is maximized through resource overcommitment. This instance class is a cost-effective option and suitable for scenarios where performance stability is not critical.

Suitable for scenarios that have high requirements on cost-effectiveness.

Enhanced II

With a leading network acceleration engine and Data Plane Development Kit (DPDK) fast packet processing mechanism, this instance class provides higher network performance and computing power.

Suitable for websites and web applications that require high database compute and network performance

Table 2 lists the specifications of replica set instances.

Table 2 Replica set instance specifications

CPU Type

Specifications

vCPUs

Memory (GB)

Flavor ID

Default Maximum Number of Connections

Range of Connections

x86

General-purpose

2

4

dds.mongodb.s6.large.2.repset

1000

200-21000

2

8

dds.mongodb.s6.large.4.repset

1000

200-21000

4

8

dds.mongodb.s6.xlarge.2.repset

3000

200-21000

4

16

dds.mongodb.s6.xlarge.4.repset

3000

200-21000

8

16

dds.mongodb.s6.2xlarge.2.repset

8000

200-21000

8

32

dds.mongodb.s6.2xlarge.4.repset

8000

200-21000

Enhanced II

2

8

dds.mongodb.c6.large.4.repset

1000

200-21000

2

16

dds.mongodb.c6.large.8.repset

1000

200-21000

4

16

dds.mongodb.c6.xlarge.4.repset

3000

200-21000

4

32

dds.mongodb.c6.xlarge.8.repset

3000

200-21000

8

32

dds.mongodb.c6.2xlarge.4.repset

8000

200-21000

8

64

dds.mongodb.c6.2xlarge.8.repset

8000

200-21000

16

64

dds.mongodb.c6.4xlarge.4.repset

16000

200-21000

16

128

dds.mongodb.c6.4xlarge.8.repset

16000

200-21000

32

128

dds.mongodb.c6.8xlarge.4.repset

16000

200-21000

32

256

dds.mongodb.c6.8xlarge.8.repset

16000

200-21000

64

256

dds.mongodb.c6.16xlarge.4.repset

16000

200-21000

Kunpeng

-

2

4

dds.mongodb.large.arm2.repset

1000

200-21000

-

2

8

dds.mongodb.large.arm4.repset

1000

200-21000

-

4

8

dds.mongodb.xlarge.arm2.repset

3000

200-21000

-

4

16

dds.mongodb.xlarge.arm4.repset

3000

200-21000

-

8

16

dds.mongodb.2xlarge.arm2.repset

8000

200-21000

-

8

32

dds.mongodb.2xlarge.arm4.repset

8000

200-21000

-

16

32

dds.mongodb.4xlarge.arm2.repset

16000

200-21000

-

16

64

dds.mongodb.4xlarge.arm4.repset

16000

200-21000

-

32

64

dds.mongodb.8xlarge.arm2.repset

16000

200-21000

-

32

128

dds.mongodb.8xlarge.arm4.repset

16000

200-21000

-

64

128

dds.mongodb.16xlarge.arm2.repset

16000

200-21000

-

64

256

dds.mongodb.16xlarge.arm4.repset

16000

200-21000

Historical Instance Specifications

For details about the range of connections of instances created before July 2021, see the following table.

Table 3 Replica set instance specifications

CPU Type

Specifications

vCPUs

Memory (GB)

Flavor ID

Default Maximum Number of Connections

Range of Connections

x86

General-purpose

2

4

dds.mongodb.s6.large.2.repset

400

200-1000

2

8

dds.mongodb.s6.large.4.repset

400

200-1000

4

8

dds.mongodb.s6.xlarge.2.repset

1000

200-3000

4

16

dds.mongodb.s6.xlarge.4.repset

1000

200-3000

8

16

dds.mongodb.s6.2xlarge.2.repset

4000

200-8000

8

32

dds.mongodb.s6.2xlarge.4.repset

4000

200-8000

Enhanced

2

8

dds.mongodb.c3.large.4.repset

400

200-1000

4

16

dds.mongodb.c3.xlarge.4.repset

1000

200-3000

8

32

dds.mongodb.c3.2xlarge.4.repset

4000

200-8000

16

64

dds.mongodb.c3.4xlarge.4.repset

8000

200-16000

32

128

dds.mongodb.c3.8xlarge.4.repset

8000

200-16000

60

256

dds.mongodb.c3.15xlarge.4.repset

8000

200-16000

Enhanced II

2

8

dds.mongodb.c6.large.4.repset

400

200-1000

4

16

dds.mongodb.c6.xlarge.4.repset

1000

200-3000

8

32

dds.mongodb.c6.2xlarge.4.repset

4000

200-8000

16

64

dds.mongodb.c6.4xlarge.4.repset

8000

200-16000

32

128

dds.mongodb.c6.8xlarge.4.repset

8000

200-16000

64

256

dds.mongodb.c6.16xlarge.4.repset

8000

200-16000

Kunpeng

-

2

4

dds.mongodb.large.arm2.repset

400

200-1000

-

2

8

dds.mongodb.large.arm4.repset

400

200-1000

-

4

8

dds.mongodb.xlarge.arm2.repset

1000

200-3000

-

4

16

dds.mongodb.xlarge.arm4.repset

1000

200-3000

-

8

16

dds.mongodb.2xlarge.arm2.repset

4000

200-8000

-

8

32

dds.mongodb.2xlarge.arm4.repset

4000

200-8000

-

16

32

dds.mongodb.4xlarge.arm2.repset

8000

200-16000

-

16

64

dds.mongodb.4xlarge.arm4.repset

8000

200-16000

Helpful Links

How Do I Change the Maximum Number of Connections for a Replica Set Instance?

You can change the maximum number of connections to an instance by modifying the net.maxIncomingConnections parameter. For details about how to change parameter values, see Editing a Parameter Template.

How Do I Purchase a Replica Set Instance?

For details, see Buying a Replica Set Instance.

How Do I Change the CPUs and Memory of a Replica Set Instance?

For details, see Changing the CPU or Memory of a Replica Set Instance.

How Do I Scale Up Storage of a Replica Set Instance?

For details, see Scaling Up Storage.

Parent Topic: Instance Specifications