Amazon Database Migration Service

Overview

Amazon Database Migration Service (AWS DMS) moves relational, NoSQL and warehouse data stores to AWS or between cloud and on-premises environments. It is best for teams migrating databases to AWS or keeping data synchronized during a move. Its range of migration patterns is useful, but the requirement that at least one endpoint be on RDS or EC2 rules out on-premises-to-on-premises replication.

Key features

DMS handles both one-time migrations and ongoing replication, for moves between like database engines as well as between different engines. AWS says it supports more than 20 databases and data warehouses as source and target endpoints, giving teams with mixed estates options for consolidation. The endpoint rule is a real boundary, not a minor qualification: DMS is not the right fit when both databases must remain on premises.

DMS Schema Conversion assesses schemas and converts most database code objects, including views, stored procedures and functions. It also identifies objects requiring manual conversion, which can help teams scope migration work without implying that every object will transfer automatically.

DMS Serverless provisions and scales migration capacity according to transaction volume, with hourly charges measured in DCUs. That removes the need to set replication capacity in advance, but cost varies with data volume and the maximum DCU setting. On-demand instances instead bill hourly, without a long-term commitment; instance type and AWS Region affect the price, and additional log storage may cost extra. For steady, eligible DMS usage, Database Savings Plans trade a one-year commitment to a specific usage amount for savings of up to 20%.

For resilience, the Multi-AZ option uses redundant replication instances, and DMS can resume a migration after an interruption. CloudTrail and CloudWatch Logs integrations, plus API and AWS CLI controls, support task automation and custom monitoring. Security controls include TLS 1.2 for API clients (AWS recommends TLS 1.3), resource-based access policies, PrivateLink VPC endpoints, SSL/TLS-protected database connections, VPC-hosted replication instances and masking for specified sensitive columns.

Pricing

AWS DMS combines paid usage with an AWS Free Tier offer. The free plan costs nothing and provides $100 in credits, with up to an additional $100 for activating foundational AWS services. Credits are valid for up to 12 months; after they run out, a Paid Plan is required to continue using DMS. Credits are unavailable in AWS GovCloud (US) and China.

AWS DMS Serverless uses hourly capacity billing, with the price varying by data volume and maximum DCU setting. On-demand instances are billed hourly with no long-term commitment, and the rate varies by instance type and Region; log storage may add cost. Database Savings Plans have custom pricing and require a one-year commitment to a specific amount of eligible usage, in exchange for savings of up to 20% when usage is consistent. Serverless suits variable workloads; on-demand fits teams avoiding commitments, while the savings plan is better for predictable usage that can support its term.

Platforms

DMS is offered as a SaaS service on the web, with an API for integration and task management. Discovery and assessment, database migration and continuous replication are supported.

Who it's for

DMS is a strong fit for organizations moving self-managed databases and analytics workloads to AWS, especially when a migration needs ongoing replication or spans different database engines. Teams should look elsewhere if both endpoints must stay on premises, or if they need costs independent of usage and capacity choices.

Pros and cons

• Broad migration coverage: More than 20 database and warehouse endpoints, with homogeneous and heterogeneous moves, can accommodate varied estates.
• Useful continuity options: Ongoing replication, Multi-AZ redundancy and resumption after interruption support migrations that cannot rely on a single uninterrupted run.
• Conversion assistance, not full automation: Schema Conversion handles most code objects and flags manual work, but remaining objects still need attention.
• Endpoint constraint: At least one endpoint must be on RDS or EC2, excluding on-premises-only replication.
• Usage-sensitive costs: Serverless charges depend on DCUs, data volume and maximum capacity, while instance and log-storage costs can also vary.

Alternatives

SymmetricDS is worth considering for a free-forever Community plan under AGPL v3 and support across mobile, desktop, server and web platforms. MySQL is a relevant alternative for teams seeking a database with a Community Edition that includes replication and high-availability components. Debezium offers an open-source distributed change data capture platform under Apache License 2.0. TiCDC is another free, open-source option. Artie has a free plan capped at 1M billable rows per month and two active pipelines, with backfills included. Bucardo is a free, open-source choice for Linux and macOS. Couchbase XDCR is an alternative to consider for Couchbase deployments. Estuary offers a free plan alongside a $100.00 per month pay-as-you-go plan. For broader comparisons, browse Data Replication Software or Cloud Migration Tools.

Verdict

Choose AWS DMS if you are moving databases to AWS and need broad engine support, ongoing replication and recovery options around the migration. Its clearest drawback is the RDS-or-EC2 endpoint requirement; teams that need on-premises-to-on-premises replication should choose another tool.