AWS Application Migration Service (MGN) allows businesses to perform block-level replication of their on-premises workloads and shift them into the AWS cloud with minimal friction. Often referred to as a “lift-and-shift” tool, MGN eliminates the need to re-architect applications, enabling businesses to move their workloads quickly while keeping operational changes to a minimum.

MGN works with almost any on-premises server—whether it’s physical or virtual, including environments like VMware, Hyper-V, or even bare metal. You can even use this to migrate your VMs from other public cloud providers to AWS. The tool continuously replicates source servers at the block level, meaning it mirrors changes as they happen, ensuring that the target environment on AWS is always in sync. This allows for a smooth cutover when the time comes to switch to ec2 instances.

One of the biggest challenges in cloud migrations is balancing the need for speed with the need for stability. Traditional migrations require rebuilding or refactoring applications, which can be labour-intensive, time-consuming, and risky for business-critical applications. Furthermore, downtime can be disruptive and costly for operations, particularly if migrations take longer than expected.

AWS MGN simplifies this by providing a streamlined, automated migration solution with minimal disruption. By replicating your environment at the block level, it allows you to transition from on-premises infrastructure to AWS without altering your existing systems, and downtime is minimised to the cutover window itself.

Establishing the Baseline

The migration begins with block-level replication of systems, meaning MGN continuously syncs data from your source environment to AWS at the lowest possible level. This ensures that your AWS instance is always in a state that reflects the most recent data from your on-premises servers.

Here’s a breakdown of the key steps during the initial phase:

• Install MGN Agents: Agents are deployed on the on-prem servers (VMware, Hyper-V, bare metal, etc.).
• Initial Sync: MGN initiates block-level replication, copying your existing environment to AWS. This sync runs in the background without impacting ongoing business operations.

Testing: Dry Run

One of the standout features of MGN is its testing capability. Before you cut over to your new cloud environment, MGN allows you to hydrate and test the system in a fully replicated AWS environment. During this phase:

• Test System Hydration: After replication, a test instance is launched in AWS.
• Test Verification: Administrators can verify that the application works in the AWS environment, validate configurations, and ensure that performance is up to expectations.
• Minimal Risk: Since the test instance is separate from production, any errors or adjustments can be handled without impacting live operations.

Final Sync and Cutover

Once testing is complete and the system has been validated, the final phase of migration begins:

• Final Replication: MGN resyncs your source environment to the AWS destination to ensure all recent changes are copied over.
• Cutover: After syncing is complete, on-premises servers are shut down, and the cutover instance in AWS is launched. You are now fully operating in AWS with no further dependency on the on-prem servers.

For environments where downtime must be minimised, MGN’s efficient block-level replication keeps the cutover period short, ensuring minimal disruption.

Post-Migration Clean-up and Optimisation

Once the  migration is complete:

• Disconnect MGN: The MGN agents are decommissioned, and any unnecessary infrastructure in AWS can be torn down.
• Optimise AWS Environment: After the cutover, businesses can take advantage of AWS’s scalability and flexible pricing models to optimise their infrastructure for cost efficiency and performance. This may involve moving instances to reserved or spot pricing or refactoring applications gradually to make use of cloud-native services like AWS Lambda, RDS, or Elastic Beanstalk.

Pros

1. Fast and Easy Setup
   • Setting up MGN in AWS is straightforward. The MGN agent is installed on each server, and the service handles replication automatically. Even if you lack deep cloud expertise, MGN provides clear guidance through its console to guide you through the entire process.
2. Lift and Shift Simplicity
   • No refactoring, rebuilding, or modifying your application stack. MGN is a true “lift-and-shift” solution, ideal for businesses that need to move quickly without making changes to the application architecture.
3. Continuous Block-Level Replication
   • MGN replicates the entire server at the block level. As changes are made on the source server, they are immediately reflected in the destination AWS environment. This ensures that you can cut over with minimal data loss or downtime.
4. No Complex Network Requirements to Start
   • Unlike other migration tools that require direct connections (DX) or VPNs between on-prem and cloud, MGN works via the public internet. This reduces the complexity and cost of setting up secure connections, especially when time constraints are a factor.

Cons

1. Manual Cutover Process
   • The cutover process involves some manual steps, requiring administrators to migrate servers through the MGN console. For large-scale migrations, this can become labour-intensive and time-consuming.
2. No Layer 2 Network Extension
   • If your application requires Layer 2 network extensions, such as for certain broadcast protocols or VLANs, MGN does not natively support this, limiting its use for some network-heavy applications.
3. Complex Environments May Require Additional Work
   • For environments with domain-joined servers, legacy configurations, or custom network setups, MGN might require additional effort to ensure all configurations are preserved after migration.
4. No Live Migration
   • There is no live migration using MGN, a downtime is required for servers to be migrated to AWS. This could impact business continuity and may not be suitable for some businesses.

MGN is best suited for businesses looking for rapid migration with minimal disruption. Here are a few scenarios where MGN excels:

• Data Centre Exit: If your organisation is planning to close an on-prem data centre and move everything to AWS, MGN is perfect for moving workloads quickly.
• Disaster Recovery: MGN provides continuous replication, which can be useful as part of a disaster recovery solution, ensuring that you always have an up-to-date copy of your environment in AWS.
• Development and Testing: Need a replica of your production environment for testing without disrupting operations? MGN’s block-level replication can help you spin up test instances of production systems with minimal fuss.
• VMC migration to EC2: MGN can also be used to migrate your existing VMware on Cloud workloads to AWS EC2.

AWS Application Migration Service (MGN) offers a fast, reliable, and cost-effective way to migrate on-premises workloads to the cloud. While it may not support every network configuration and the cutover process involves some manual effort, its continuous replication, ease of use, and “lift-and-shift” simplicity make it a fantastic tool for businesses looking to minimise downtime during cloud migration.

For organisations prioritising agility and scalability without the burden of rebuilding applications, AWS MGN is a perfect fit. By following the structured migration process outlined above, businesses can reduce risk, control costs, and ensure a smooth transition to the AWS cloud.

Whether you are migrating to escape the constraints of on-prem infrastructure or are looking for a disaster recovery solution, AWS MGN provides a seamless, powerful tool to help you achieve your cloud migration goals and we at Mantalus can certainly help you with your journey to AWS.