AWS DMS for Data Migration and more

 🧠 DBA Tip: AWS DMS Isn’t Just for Migrations — It’s a Hidden Gem for Continuous Replication

If you’ve ever had to move a live production database with near-zero downtime, AWS Database Migration Service (DMS) can save your weekend.

Here’s a quick example setup I recently used to replicate an on-prem Oracle DB to Amazon Aurora PostgreSQL — while keeping both in sync until cutover 👇

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⚙️ Step 1: Create a Replication Instance

aws dms create-replication-instance \
  --replication-instance-identifier dms-repl-prod \
  --replication-instance-class dms.r6i.large \
  --allocated-storage 100 \
  --multi-az

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⚙️ Step 2: Define Source and Target Endpoints

aws dms create-endpoint \
  --endpoint-identifier oracle-src \
  --endpoint-type source \
  --engine-name oracle \
  --username admin \
  --password '****' \
  --server-name oradb01.example.com \
  --port 1521 \
  --database-name PRODDB

aws dms create-endpoint \
  --endpoint-identifier aurora-target \
  --endpoint-type target \
  --engine-name aurora-postgresql \
  --username dbauser \
  --password '****' \
  --server-name aurora-cluster.cluster-xyz.us-east-1.rds.amazonaws.com \
  --port 5432 \
  --database-name prod_migrated

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⚙️ Step 3: Create and Start the Migration Task

aws dms create-replication-task \
  --replication-task-identifier oracle-to-aurora-task \
  --source-endpoint-arn arn:aws:dms:...:endpoint/oracle-src \
  --target-endpoint-arn arn:aws:dms:...:endpoint/aurora-target \
  --migration-type full-load-and-cdc \
  --table-mappings file://table-mappings.json \
  --replication-task-settings file://task-settings.json

Then start it:

aws dms start-replication-task \
  --replication-task-arn arn:aws:dms:...:task/oracle-to-aurora-task \
  --start-replication-task-type start-replication

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🔍 Pro Tips for DBAs:

• Use --migration-type full-load-and-cdc to keep the target updated while users are still writing to the source.

• Check task status & latency:

  aws dms describe-replication-tasks \
    --filters "Name=replication-task-id,Values=oracle-to-aurora-task" \
    --query "ReplicationTasks[*].{Status:Status,CDCStartTime:ReplicationStats.FullLoadProgressPercent}"
  

• Always validate with:

  aws dms describe-table-statistics --replication-task-arn <task-arn>
  

• Combine with AWS SCT (Schema Conversion Tool) for object conversion before DMS handles data replication.

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💡 Bonus use case: You can repurpose DMS for ongoing replication — e.g., feeding an analytics cluster or keeping a DR instance up to date.

Curious — how many of you have used DMS for continuous sync rather than one-time migrations?

#AWS #DMS #DBA #CloudMigration #PostgreSQL #Oracle #AWSCLI #DataEngineering #DevOps