Tutorial / Cram Notes
Amazon Web Services (AWS) provides two primary tools to facilitate this process: AWS Database Migration Service (AWS DMS) and AWS Schema Conversion Tool (AWS SCT). These tools serve different functions in the migration process and are often used in conjunction to provide a seamless transition.
AWS Database Migration Service (AWS DMS)
AWS DMS is a service that helps you migrate databases to AWS quickly and securely. The source database remains fully operational during the migration, minimizing downtime. AWS DMS can migrate your data to and from most of the widely used commercial and open-source databases.
Key Features:
- Supports heterogeneous migrations between different database platforms, such as Oracle to Amazon Aurora or Microsoft SQL Server to PostgreSQL.
- Supports homogeneous migrations such as Oracle to Oracle.
- Provides continuous data replication with high-availability and failover support.
- Comes with monitoring and notification features for migration tasks.
Migration Process with AWS DMS:
- Set up a replication instance: This instance will be used to perform the migration.
- Specify source and target databases: Connect to your source database and the target database on AWS.
- Choose the migration type: You can opt for full data load, which migrates all the data or choose ongoing data changes to replicate changes continuously.
- Start the migration task: AWS DMS transfers the data from the source to the target database.
AWS Schema Conversion Tool (AWS SCT)
AWS SCT helps convert your source database schema and most of the database code objects, including views, stored procedures, and functions, to a format compatible with the target database. It’s an essential tool for heterogeneous database migrations, where you’re moving from one type of database to a different type.
Key Features:
- Analyzes the entire database schema of your source database.
- Automatically converts the schema of the source database to the schema of the target database.
- Provides guidance and an action plan for objects that cannot be automatically converted.
- Supports complex data warehouses conversions.
Schema Conversion Process with AWS SCT:
- Connect to the source database: Launch AWS SCT and connect to your source database.
- Assess the conversion: Perform an assessment report to get an overview of what can and cannot be automatically converted.
- Convert the schema: Apply the schema conversion rules, and make manual changes when required.
- Apply the converted schema: Create the schema in the target database.
- Migrate the data: Use AWS DMS to migrate data from the source to the target data store.
Integration of AWS DMS and AWS SCT
AWS DMS and AWS SCT are often used together to ease complex database migrations. Here’s a typical migration workflow:
- Use AWS SCT to convert the source database’s schema and code objects to the target database format.
- Review and manually refine any items that AWS SCT cannot automatically convert.
- Apply the AWS SCT-generated schema to the target database.
- Use AWS DMS to migrate the actual data from the source to the newly created schema in the target database.
Comparison Table
| Features/Tools | AWS DMS | AWS SCT |
|---|---|---|
| Migrates Data | Yes | No (Used in conjunction with AWS DMS) |
| Converts Schema | No | Yes |
| Supports Homogeneous Migrations | Yes | Limited |
| Supports Heterogeneous Migrations | Yes | Yes |
| Continuous Data Replication | Yes | Not applicable |
| Database Code Conversion | No | Yes |
| High-Availability Support | Yes | No |
| Detailed Assessment Reports | No | Yes |
In preparing for the AWS Certified Solutions Architect – Professional (SAP-C02) exam, understanding these tools is crucial. Practical experience with them will go a long way in helping you understand how to architect complex database migrations and manage post-migration performance and maintenance tasks. Consider setting up a small, hands-on project where you migrate a sample database using AWS DMS and AWS SCT to gain valuable experience with these tools.
Practice Test with Explanation
True or False: AWS Database Migration Service (AWS DMS) supports homogeneous database migrations only, such as Oracle to Oracle.
- True
- False
Answer: False
Explanation: AWS DMS supports both homogeneous migrations (like Oracle to Oracle) and heterogeneous migrations (like Microsoft SQL Server to Amazon Aurora).
The AWS Schema Conversion Tool (AWS SCT) is used to:
- A. Monitor database performance
- B. Convert source database schema to a format compatible with the target database
- C. Migrate the actual data from one database to another
- D. Backup databases into S3
Answer: B
Explanation: AWS SCT’s primary function is to convert source database schemas to a target format compatible with the desired target database.
True or False: AWS DMS can be used to migrate databases to AWS from on-premises environments, other cloud platforms, or other regions within AWS.
- True
- False
Answer: True
Explanation: AWS DMS is a versatile tool that can handle migration from various sources, including on-premises databases, other cloud environments, and different AWS regions.
During a database migration using AWS DMS, which of the following tasks are performed by the service?
- A. Schema conversion
- B. Data replication
- C. Continuous data synchronization
- D. All of the above
Answer: B
Explanation: AWS DMS primarily performs data replication. Schema conversion is handled by AWS SCT, and continuous data synchronization is just one of the features provided by AWS DMS for ongoing replication needs.
True or False: AWS SCT can automatically resolve all compatibility issues during schema conversion.
- True
- False
Answer: False
Explanation: While AWS SCT can resolve many conversion challenges, it might not be able to automatically fix all compatibility issues. Some might need manual intervention.
What types of migrations does AWS DMS support?
- A. Full Load
- B. Full Load plus Continuous Data Capture (CDC)
- C. CDC only
- D. All of the above
Answer: D
Explanation: AWS DMS supports full load migrations, full load migrations with the option of continuous data capture, and continuous data capture by itself for ongoing data replication.
True or False: The AWS Schema Conversion Tool (SCT) can directly migrate your data from one database to another.
- True
- False
Answer: False
Explanation: AWS SCT does not perform the actual data migration; it helps convert the database schema from the source database to match that of the target database. The actual data migration is done by AWS DMS.
When using AWS DMS, what is the role of replication instances?
- A. Store the migrated data
- B. Convert the database schemas
- C. Perform the actual data migration process
- D. Backup the source database
Answer: C
Explanation: The replication instance in AWS DMS performs the actual data migration between source and target databases.
True or False: AWS DMS can be used to consolidate multiple source databases into a single target database.
- True
- False
Answer: True
Explanation: AWS DMS supports consolidation scenarios, allowing you to combine data from multiple source databases into a single target database.
AWS DMS supports change data capture (CDC), which is:
- A. A full load of the source database
- B. A technique to capture only the changes made to the source database after the initial migration
- C. The process of converting database schemas
- D. A backup method for databases
Answer: B
Explanation: Change Data Capture (CDC) is a feature in AWS DMS that allows the service to capture and replicate incremental changes from the source database after an initial full load.
True or False: When performing a database migration with AWS DMS, you can’t use your source database for normal operations during the migration process.
- True
- False
Answer: False
Explanation: AWS DMS supports minimal downtime migrations, which means you can continue to use your source database while the migration takes place.
During a migration, how does AWS SCT assist in converting SQL queries and stored procedures?
- A. By rewriting them to work with the target database engine
- B. By optimizing them for performance on the source database
- C. By storing them in Amazon S3 for archival purposes
- D. By encrypting them for secure transfer to the target database
Answer: A
Explanation: AWS SCT helps convert custom SQL code, such as queries and stored procedures, to be compatible with the target database engine’s syntax and semantics.
Interview Questions
What is AWS Database Migration Service (AWS DMS), and how does it support heterogeneous migrations?
AWS DMS is a service that enables the migration of relational databases, data warehouses, and other types of data stores to AWS. It supports both homogeneous migrations (e.g., Oracle to Oracle) and heterogeneous migrations (e.g., Oracle to Amazon Aurora), allowing for the transformation of the source database schema and data types to match those of the target database.
Can you describe a scenario where you would use AWS Schema Conversion Tool (AWS SCT)?
AWS SCT would be used in a scenario where there needs to be a conversion from one database engine to another, such as from Microsoft SQL Server to Amazon Aurora. AWS SCT facilitates the conversion of the database schema, including the database code like stored procedures and functions, to a format compatible with the target database engine.
What are some considerations to keep in mind when planning a database migration using AWS DMS?
When planning a database migration using AWS DMS, considerations include the size of the database, network bandwidth and connectivity, type and complexity of the source and target database engines, the potential need for schema conversion, security requirements (like encrypting data in transit and at rest), and minimizing downtime.
How does AWS DMS ensure minimal downtime during database migrations?
AWS DMS ensures minimal downtime by using a replication feature that continuously captures data changes at the source database and applies them to the target database during the migration process. This enables the source database to remain operative, and after the initial load is finished and the changes are in sync, you can switch to the target database with minimal downtime.
What types of data stores can AWS DMS replicate data from and to?
AWS DMS can handle migration to and from most of the popular relational databases, including Amazon Aurora, PostgreSQL, MySQL, MariaDB, Oracle, SAP ASE, SQL Server, and IBM Db It can also migrate data to and from various non-relational databases and data warehouses such as MongoDB and Amazon Redshift.
How does AWS DMS handle large-scale migrations where there are terabytes of data to be transferred?
For large-scale migrations with terabytes of data, AWS DMS handles the transfer by breaking down the migration into tasks and using parallel processing when possible. It also allows for table mapping and selection, so large tables can be migrated incrementally using a primary key.
Can AWS DMS be used for continuous data replication?
Yes, AWS DMS can be used for continuous data replication. It allows real-time replication with high availability, enabling the source and target databases to stay in sync even after the initial transfer is done, which is useful for disaster recovery scenarios or keeping a standby database up-to-date.
What does the AWS Schema Conversion Tool do specifically to help migrate databases?
The AWS Schema Conversion Tool automates much of the process of converting the source database schema and code to match the target database, including the SQL code for stored procedures, functions, triggers, and views. It provides a detailed assessment report that highlights the manual effort required to complete the conversion and suggests equivalent AWS services for unsupported database functionality.
Is there any performance impact on the source database while using AWS DMS?
There might be a minimal performance overhead on the source database during initial data load and ongoing replication, as AWS DMS needs to read database logs or use database triggers to capture the change data. However, AWS DMS is designed to have a minimal impact, and any performance impact can be managed by scheduling migrations during periods of low database activity.
How does AWS handle security and compliance when using AWS DMS and AWS SCT?
AWS provides various security measures such as end-to-end encryption, network isolation using Amazon Virtual Private Cloud (VPC), Identity and Access Management (IAM) for access control, and monitoring through AWS CloudTrail. Compliance is addressed through adherence to different compliance programs that AWS is part of, which allows users to meet certain regulatory requirements during the migration.
What strategies can you use to test and validate the database migration process when using AWS DMS?
Strategies for testing and validation include using the AWS SCT to perform a pre-migration assessment, running test migrations with sample datasets, performing full load migrations in a staging environment, using data validation feature in AWS DMS to ensure data integrity, and testing the application functionality with the migrated database before going live.
How would you monitor and troubleshoot the database migration process in AWS DMS?
You can monitor migrations using CloudWatch, which provides metrics on the replication instance and task performance. You can also enable CloudTrail for auditing API calls and operations made by AWS DMS. For troubleshooting, AWS DMS provides notifications and detailed task logs that can help identify and resolve issues that might arise during migrations.
Great blog post! AWS DMS and AWS SCT are absolute lifesavers for database migrations. Highly recommended for SAP-C02 exam preparation!
I found AWS DMS very helpful for my recent database migration project. It simplifies the entire process!
Thanks for the detailed post on AWS Schema Conversion Tool. It really helped me understand its use cases better.
Can someone explain the main differences between AWS DMS and AWS SCT?
I had some issues with performance using AWS DMS for a large dataset. Anyone else faced this?
Is it possible to migrate both homogeneous and heterogeneous databases using AWS DMS?
Great insights! Much appreciated!
I’ve used AWS SCT for converting from MySQL to PostgreSQL and it worked seamlessly. Highly recommend!