Database Migration Service

AWS Database Migration service allows AWS customers to easily migrate Production databases to AWS with minimal downtime. It is currently available for preview in US East (N. Virginia) region.Setting up Database Migration toll is easy and quick it takes about 10-15 minutes to setup.During migration of databases, sources database remains operationally active. DMS supports homogeneous migrations and also heterogeneous migrations of databases like Oracle to Amazon Aurora and MySQL to PostgreSQL. AWS database migration service can migrate data using commercial and open-sources databases.

Why AWS Database Migration Service instead of  own self-managed replication solution.

 AWS Database Migration Service is easy and faster to setup and use. Replication tasks can be set-up   in minutes instead of hours or days, Instead of the self-managed replication solutions that have to be installed and configured. AWS Database Migration Service monitors replication tasks, network or host failures, and automatically provisions a host replacement in case of failures that can’t be repaired.

DMS Schema conversion tool for Dissimilar Engines:

Usually Heterogeneous migrations are very complex and time consuming to overcome the problems caused during Heterogeneous migrations. AWS has come up with database migration Schema Conversion Tool which makes heterogeneous migrations more simpler and easier by automatically converting entire database schema and majority of custom code of the source database to a format compatible with target database.it converts sources database schema and code.The changes to the source database that occur during the migration process are automatically replicated to the target    Below Architecture Diagram gives an idea of how Schema conversion Tool works for Dissimilar engines

 DMS Migration with Dissimilar engines Using Schema conversion Tool.

Database Migration between Dissimilar engines with different Availability Zones.

In Database Migration Service we are creating Replication Instance which is connected with Source and Target Endpoints then creating Replication Task once Replication instance is created automatically Migration will be started once it is done the task will be in Stopped state.Here is a detailed tutorial on how to achieve the Database Migration.

Step 1: Creating DMS Replication Instance

• Click on Launch Replication Instance in DMS Dashboard.

• Enter Replication Instance Name.
• Enter Description of Replication Instance(Not Mandatory).
• Select the Instance class from the set of Available Instance classes.
• Select the VPC Name in which Replication instances need to be created.
• Click on Advanced.                                                                                                                                                      
• Select the Replication subnet group.
• Select the Availability Zone(Replication instance need to be in same AZ as that Source database Engine)
• Select the Master key(KMS Key) for Encryption Purpose during migration.
• Click on Create Replication Instance.                                                                                                                            

Step 2: Creating DMS Endpoints                                                                                 

• Click on Endpoints>>Create Endpoint

• Enable Endpoint type as Source for Creating the Source Endpoint.
• Enter Endpoint Identifier for source Endpoint.
• Select the Source engine.
• Enter Server address(Source RDS Database Endpoint)
• Enter Port number of source Engine.
• Enter Username of source RDS database.
• Enter Password of source RDS database.
• Enter Database Name of source RDS database.
• Click on Advanced.

• Connection string is not mandatory aws provides connection string by default .
• Select Master key(KMS key).
• Enter VPC name you want Endpoint to use.
• Select Replication Instnces.
• Click on Run Test to test endpoint connection it will generate a statement connection tested successfully.
• Click on SAVE.
• Create Target endpoint as we have created for Source and Test connection Endpoint for target Using Run Test

•  Now Click on Endpoints  you should be able to see the endpoints created for the  source and target in this case MySQL is source and PostgreSQL is Target Endpoint.                                                                                                                                       

Step 3: Creating DMS Replication Task                                                                                               

• Enter Task name.
• Select Replication Instance which was created in earlier steps.
• Select the source endpoint(MYSQL Endpoint).
• select Target endpoint (PostgresSQL Endpoint).
• select the Migration type as Migrate Existing Data.
• Enable Mapping Method option as default.
• Click on Create Task.                                                                                                                                                        
• Once the Task is created Migration will be Started initial status of task will be creating,once migration is started task status becomes running.                                                                                   
• When Migration is completed automatically Task status becomes Stopped.

Database migration features:

1) Automated and continuous data replication.

2) Self-healing and Resilient.

1) Automated and continuous data replication: once the database migration process begins the data capture capability of  DMS continuously captures  all data changes from sources database to target it minimizes downtime by enabling you to keep the source database operational during the migration AWS Database Migration Service can perform continuous replication of data from one database to another and between homogeneous or heterogeneous databases.

2) Self-healing and Resilient: AWS Database Migration Service makes it easy to recover from network and host failures. It continually monitors source and target databases, network connectivity, and the infrastructure running the replication process and issues alerts when a failure occurs.

Benefits:

• Minimizes Downtime During Migrations.
• Fast and Easy to Set-up.
• Low Cost.
• Supports All Widely Used Databases.
• Reliability.

Sources and targets supported by AWS Database Migration Service
AWS Database Migration Service supports both homogeneous and heterogeneous Source and targets.Supported databases  include:

•  Oracle.
•  PostgreSQL.
•  MySQL.

Pricing:                                                                      

In  AWS Database Migration Services. We only pay for the compute resources used during the migration process (Database migration instance that moves your data from your source database to your target database).

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