Module 11: Migrating Workloads - Advanced Architecting on AWS

🎯 Module Objectives

Apply the 7 Rs migration strategies to different workloads
Use AWS Migration Hub for centralized tracking
Migrate servers with Application Migration Service (MGN)
Migrate databases with DMS and Schema Conversion Tool
Transfer data with DataSync and Transfer Family

🔄 The 7 Rs of Migration

Strategy	Description	Effort	Example
Retire	Decommission — no longer needed	None	Legacy apps with no users
Retain	Keep on-premises (not ready)	None	Mainframe with dependencies
Rehost	Lift-and-shift (move as-is)	Low	VM → EC2 with MGN
Relocate	Move without changes (VMware→VMC)	Low	vSphere → VMware Cloud on AWS
Replatform	Lift-tinker-shift (minor changes)	Medium	SQL Server → RDS, Java → Beanstalk
Repurchase	Move to SaaS	Medium	On-prem CRM → Salesforce
Refactor	Re-architect for cloud-native	High	Monolith → microservices on ECS

🖥️ Application Migration Service (MGN)

Purpose: Lift-and-shift server migration (rehost strategy)
Agent-based: Install replication agent on source servers
Continuous replication: Block-level replication to AWS (staging area)
Testing: Launch test instances without affecting replication
Cutover: Launch production instances, update DNS, decommission source
Supported sources: Physical, VMware, Hyper-V, Azure VMs, other clouds

MGN workflow: Install agent → Continuous replication → Test launch → Cutover → Finalize. Near-zero downtime because data replicates continuously until cutover.

🗃️ Database Migration Service (DMS)

Feature	Details
Migration types	Full load, Full load + CDC, CDC only
CDC (Change Data Capture)	Continuous replication of ongoing changes after full load
Schema Conversion Tool	Convert schema between engines (Oracle→PostgreSQL, SQL→Aurora)
Homogeneous	Same engine (MySQL→MySQL) — direct migration
Heterogeneous	Different engines — requires SCT first
Sources	Oracle, SQL Server, MySQL, PostgreSQL, MongoDB, S3, etc.
Targets	RDS, Aurora, DynamoDB, S3, Redshift, OpenSearch, etc.

📡 Data Transfer Options

AWS DataSync

Online data transfer. NFS/SMB/HDFS → S3/EFS/FSx. Automated scheduling. Bandwidth throttling. Up to 10 Gbps per agent.

Transfer Family

Managed SFTP/FTPS/FTP/AS2 endpoints. Files land in S3 or EFS. Replace legacy file transfer servers.

Snow Family

Offline transfer: Snowcone (8-14 TB), Snowball Edge (80 TB), Snowmobile (100 PB). For limited bandwidth.

Direct Connect

Dedicated bandwidth for large ongoing transfers. Combine with DataSync for optimal throughput.

💻 Demo: DMS Migration Task

# Create DMS replication instance
aws dms create-replication-instance \
  --replication-instance-identifier my-dms \
  --replication-instance-class dms.r5.large \
  --allocated-storage 100

# Create migration task (full-load + CDC)
aws dms create-replication-task \
  --replication-task-identifier oracle-to-aurora \
  --source-endpoint-arn arn:aws:dms:...:endpoint:source \
  --target-endpoint-arn arn:aws:dms:...:endpoint:target \
  --replication-instance-arn arn:aws:dms:...:rep:my-dms \
  --migration-type full-load-and-cdc \
  --table-mappings file://table-mappings.json

🧪 Knowledge Check

Q1: A company needs to migrate an Oracle database to Aurora PostgreSQL with minimal downtime. Which combination of tools should they use?

A) DMS full-load only B) SCT + DMS (full-load + CDC) C) mysqldump + restore D) Application Migration Service

B) SCT + DMS (full-load + CDC) — SCT converts the Oracle schema to PostgreSQL. DMS then performs full-load + CDC (Change Data Capture) for continuous replication. Cut over when CDC catches up. MGN is for server migration, not databases.

Q2: A company has 50 TB of data to migrate but only a 100 Mbps internet connection. The migration must complete within 2 weeks. What should they use?

A) DataSync over internet B) S3 Transfer Acceleration C) Snowball Edge D) DMS

C) Snowball Edge — At 100 Mbps, transferring 50 TB takes ~46 days online. Snowball Edge (80 TB capacity) can be shipped, loaded, and returned within ~1 week. For bandwidth-limited large transfers, offline is faster.

📝 Module 11 Summary

7 Rs

Retire, Retain, Rehost, Relocate, Replatform, Repurchase, Refactor. Match strategy to workload needs.

Server Migration

MGN: agent-based continuous replication. Test launches. Near-zero downtime cutover.

Database Migration

DMS: full-load + CDC. SCT for heterogeneous. Supports Oracle, SQL Server, MySQL, PostgreSQL, MongoDB.

Data Transfer

DataSync (online, scheduled). Snow Family (offline, large). Transfer Family (SFTP/FTP to S3).