The Database Migration Service of AWS DMS is based in the cloud and is optimized to migrate on-premises databases to the cloud or between two cloud providers. It can facilitate either one-time data or continual replication provided the source and the target databases are kept in sync. AWS DMSis an ideal platform to move data from relational databases, NoSQL databases, data warehouses, or any other sources of data.
Processof Data Migration with AWS DMS
There are two ways that data can be migrated to the cloud with AWS DMS depending on the attributes of the databases.
#Homogeneous database migration
This method of migration is selected when the engines of both the source and the target databases are the same. The data types, data codes, and schema structures too need to be similar. Migration here is a simple one-step process with the full database being migrated at a time once a link is established between the source and the target databases.
For AWS DMShomogeneous migration, the source database can either be running on an Amazon EC2 instance and located outside the AWS or be an Amazon RDS database. The target databases can be an Amazon RDS or an Amazon EC2 instance.
Some common types of homogeneous database migration are MySQL to Amazon Aurora, Microsoft SQL Server to Amazon RDS for SQL Server, Oracle to Amazon RDS for Oracle,MySQL to Amazon RDS for MySQL.
# Heterogeneous database migration
This form of migration is selected when the engines of the source and the target databases are not the same. The data codes, data types, and schema structures are different too. The process here involves two steps. First, the data code and the schema structure of the source databases have to be converted to match the architecture of the target database with the AWS Schema Conversion Tool. Once done, the actual AWS DMSmigration can be started. The conversion and the migration are fully handled by the DMS.
The source database can be on an Amazon EC2 instance or an Amazon RDS database that is located off-site or on-premises. The source database may be either an Amazon RDS or on Amazon EC2 instance. Some examples of heterogeneous migration are Microsoft SQL Server to MySQL, Oracle to AmazonAurora, and Oracle to PostgreSQL.
Organizations need to select one method out of the two for database migration depending on the structure of the source and target databases.
The Advantages of AWS DMS over other Migration Solutions
There are several benefits of using AWS DMSfor migrating databases.
- Traditional migration processes were time-consuming and tedious as additional hardware and software had to be installed, administered, and debugged before migration. In comparison, AWS DMSdeploys, manages, and tracks all the necessary infrastructureand migration is setup and running in minutes once the AWS DMSis configured.
- AWS DMSprovides unmatched flexibility. Users can scale up and down in data storage whenever required by paying only for the quantum of resources used. Additional storage can be downloaded in minutes if required. This is against older methods where flat one-time fees had to be paid, regardless of the volume of storage facilities used.
- AWS DMSfully supports all infrastructure related to the migration server like error reporting, software patching, and monitoring of hardware and software.
- One of the most important benefits that users get from AWS DMS is the failover feature. If during migration, there is an issue with the primary server like an outage, secondary servers whether on-site or in remote locations are automatically triggered and the migration is not stopped. Once the outage is resolved, AWS DMSworks in the reverse direction, the primary server is updated with all transactions that took place in the break period, and migration is resumed. Hence, there is no loss of data or downtime during migration.
- Users can change to a more modern and cost-effective database by migrating with AWS DMSand avail of a host of managed databases services from Amazon Relational Database Service or Amazon Aurora. They have the option to select low-cost storage platforms such as the Amazon S3 (Simple Storage Service) or data warehouses that are fullymanaged like Amazon Redshift and NoSQL platforms like Amazon DynamoDB.
- Most of the popular source database DBMS engines are supported by AWS DMSas well as a wide range of target database engines. Hence, it is very easy for users to migrate databases, irrespective of the type of engines they operate on.
- AWS DMSensures the safety and data security of the migration process. Data at rest that is in the source database is encrypted with the AWS Key Management Service while data in flight during migration is encrypted with the Secure Socket Layer (SSL).
All these features make AWS DMSa preferred option for data migration by modern-day businesses.
Limitations of AWS DMS
Despite the several advanced and cutting-edge benefits of AWS DMS,there are a few limitations too.
- Users often face conversion issues during heterogeneous migration with AWS DMSas it is handled by a third-party service, the AWS Schema Conversion Tool.
- A good amount of coding is required for moving incremental data (Change Data Capture) after full-load migration is completed. This is a time-consuming and complex activity.
- AWS DMScannot process indexes, users, and privileges that are not directly related to table data. Only partial volumes of DDL (Data Definition Language) are replicated by AWS DMS.
- These are some of the features and benefits of AWS DMS.