Amazon Web Services (AWS) offers a robust cloud infrastructure platform across multiple Regions worldwide, designed for high reliability, scalability, and cost-effectiveness. AWS Regions are isolated to ensure fault tolerance and stability, with further partitioning for enhanced network and security isolation, such as aws, aws-gov, aws-cn, and aws-iso.

As AWS expands its footprint by introducing new Regions, organizations may contemplate migrating workloads between existing Regions for various reasons, including latency improvement, compliance requirements, or market expansion. Independent software vendors (ISVs) might also seek to broaden their customer base by extending product offerings to new Regions. Successful migration involves assessing the source environment, mobilizing resources, and executing the migration process.

Build a Business Case and Consider Cost Implications

Building a comprehensive business case and understanding the cost implications are fundamental steps before embarking on any cloud migration. In the context of AWS migration, it’s imperative to consider various cost-related aspects:

1. Service Price Variation:

AWS service prices vary across Regions due to factors like data center operational costs, energy expenses, and local market conditions. For instance, the cost per hour for an Amazon EC2 t3.micro instance in the US East (N. Virginia) Region may differ from the same instance type in the Asia Pacific (Mumbai) Region. As of 2023, the hourly cost for a t3.micro instance in US East (N. Virginia) might be around $0.0116, while in Asia Pacific (Mumbai), it could be approximately $0.0132.

2. Spending Commitments:

Assess your existing commitments such as Amazon EC2 Reserved Instances (RI) and AWS Savings Plans, which are often tied to specific Regions. For example, if you have an unused RI in the source Region, selling it in the Reserved Instances Marketplace can mitigate costs. Conversely, purchasing new RIs in the target Region aligns with the specific cost structure of that Region. The impact on costs can be substantial, depending on the terms and utilization of RIs.

3. Egress Costs:

When migrating data out of the source Region, egress costs come into play. The cost varies based on the chosen transfer method. For example, using the internet for data transfer incurs a different cost than utilizing VPC peering or AWS Transit Gateway. As of 2023, the egress cost per GB might range from $0.05 to $0.12, depending on the specific method and the Regions involved. It’s crucial to factor in these costs while estimating the overall expenses associated with migrating data across Regions.

Decide the Aspects of the Workload to Migrate

Identify AWS services used in end-to-end workflows, considering deployment pipelines, day-to-day operations, and dependencies. Components for migration consideration include:

Configuration: Includes parameter groups and option groups in Amazon RDS, detailed monitoring configurations for Amazon EC2 instances, and VPC flow logs.

Code/Software Package: Involves code or software packages stored in container images (Amazon ECR) or functions (AWS Lambda).

Data: Migration of historical and ongoing data based on workload requirements. Selective data movement may be suitable for scenarios like user location-based workload splitting.

Supplemental Data: Backup, snapshots, and logs not critical for running workloads can remain in the source Region, with only newly created data in the target Region.

Ensure Workload Compatibility in the Target Region

Differences between Regions necessitate ensuring workload compatibility in the target Region before migration. Consider disparities in:

Instance Types: Verify availability of specific instance types in the target Region using tools like the describe-instance-type-offerings API for Amazon EC2.

Marketplace/Third-Party Products: Ensure availability of community AMIs and AWS Marketplace products in the target Region, accounting for potential licensing restrictions.

Service and/or Feature Availability: Confirm service and feature availability, considering variations in regional support, API differences, and service release schedules.

Runtime Versions: Check for supported runtime versions, particularly in managed services like AWS Lambda, to avoid compatibility issues.

AWS Service Quotas: Anticipate required capacity in the target Region, considering Region-specific service quotas available in the Service Quotas console.

Certification/Compliance: Validate if the target Region meets compliance requirements using reports in AWS Artifact.

Establish the Foundation in the New Region

Establishing a robust foundation in the new AWS Region is a critical step for a successful migration. This involves a comprehensive set of actions to ensure seamless operations and compliance. Let’s delve into the details:

1. Enabling AWS Services:

Activate essential AWS services in the target Region based on workload requirements. For instance, enabling Amazon S3 for storage, Amazon RDS for databases, and Amazon EC2 for compute resources. The costs associated with these services vary, with Amazon S3 storage costs ranging from $0.023 to $0.027 per GB-month as of 2023.

2. Configuring Networking:

Set up networking components such as Virtual Private Cloud (VPC), subnets, and routing tables. Establishing an AWS Direct Connect connection for secure and high-performance network access incurs costs, starting from $0.03 per GB for data transfer out over AWS Direct Connect.

3. Implementing Security Policies:

Define and implement security policies to safeguard resources in the new Region. Utilize AWS Identity and Access Management (IAM) for access control. Costs associated with IAM are negligible, typically incurred per API call at a rate of $0.0055 per thousand requests.

4. Ensuring Business Continuity:

Build resiliency into applications by configuring backup and disaster recovery mechanisms. Leveraging services like Amazon RDS automated backups incurs additional costs, with backup storage pricing ranging from $0.095 to $0.30 per GB-month.

5. Establishing Operations:

Implement robust observability measures using Amazon CloudWatch for monitoring and logging. Costs for CloudWatch vary, with custom metrics ingestion priced at $0.30 per metric per month.

6. Managing Finances:

Extend existing cloud financial management processes to cover the new Region. Implement mechanisms to track spend across Regions. Utilize AWS Cost Explorer for detailed cost analysis, with the service itself incurring minimal costs, often below $0.01 per query.

7. Addressing Governance, Risk Management, and Compliance:

Extend governance frameworks, risk management processes, and compliance measures to the target Region. Utilize AWS Config for governance and compliance, with costs ranging from $0.003 to $0.006 per configuration item recorded.

Choose Your Migration Path

Selecting the appropriate migration path depends on categorizing AWS services in your workload based on fault isolation boundaries and cross-Region capabilities:

Global Services: For services like Amazon Route 53 and CloudFront, configuration or code changes extend the data plane to the target Region.

Regional and Zonal Services with Cross-Region Capability: Services like AWS KMS, Amazon Aurora Global Database, and DynamoDB may require configuration changes to extend resources to the target Region.

All Other Services: For most regional and zonal services, options include redeploying, restoring from backups/snapshots, or replicating using migration tools like AWS DataSync.

Conclusion

Cross-Region migration demands meticulous planning, testing, and consideration of potential challenges. AWS facilitates the process with diverse migration paths, tools, and the ability to retain existing infrastructure until migration completion. Organizations must comprehensively plan for all migration elements, including failback processes for unforeseen outcomes, ensuring a seamless transition and leveraging AWS’s capabilities for successful cross-Region workload migration.