Create Replication Instance

Create replication subnet group

One of the pre-requisites of AWS DMS is to have configured a subnet group, which is a collection of subnets that can be used by the DMS Replication Instance.

  1. Select the DMS, Database Migration Service and then click on Subnet groups in the left menu and then the Create subnet group button.

Replication-instance dms

  1. In the Create replication subnet group form enter the following parameter values.

    Parameter Value
    Name dms-subnet-group
    Description Default VPC Subnet Group for DMS
    VPC select TargetVPC
    Add subnets select TargetVPC-public-a, TargetVPC-public-b

  2. Double check that all settings are correct, in particular the public subnets with TargetVPC-public in their name, and then click on the Create subnet group button.

    Replication-instance-networ

Create AWS DMS Replication Instance

In this step you will create an AWS Database Migration Service Replication Instance that initiates the connection between the source and target databases, transfers the data, and caches any changes that occur on the source database during the initial data load.

  1. Inside AWS Console, go to Services and Database Migration Service.

  2. Click on Replication instances and then on the Create replication instance button.

    Replication-instance-create

  3. On the Create replication instance screen configure a new replication instance with the following parameter values:

    Parameter Value
    Name replication-instance
    Description DMS replication instance
    Instance Class dms.t3.medium
    Engine version 3.4.5
    Allocated storage (GB) 50
    VPC TargetVPC
    Multi-AZ Dev or test workload (Single-AZ)
    Publicly accessible Checked

    replication-instance-conf

    In the Advanced security and network configuration, make sure to select the replication subnet group, Availability zone (us-west-2a) and the replication instance security group that you created earlier.

    Replication-instance-conf

  4. Click Create button.

If you get an error saying “SYSTEM ERROR MESSAGE:Cannot create a dms.t3.medium replication instance”, create the DMS replication instance again but select us-west-2b Availability Zone and if this doesn’t help - select larger instance class.