Domain 4 of 4 · Chapter 2 of 4

Choosing the migration approach

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Included in this chapter:

  • The 7 Rs: from strategy name to migration tool
  • Rehost with AWS Application Migration Service (MGN)
  • Database migration: DMS, SCT, CDC, and DMS Serverless
  • Data transfer: DataSync, Transfer Family, and Snow Family

Choosing the AWS migration / transfer service by what you are moving

DimensionMGN (Application Migration Service)DMS + SCTDataSyncSnow Family
What it movesWhole servers (OS + apps + disks)Databases (data; SCT does schema)Files & objects (NFS/SMB/HDFS/object)Bulk files/objects, offline
7 R fitRehost / relocateReplatform / refactor (DB)Any (data movement step)Any (data movement step)
Online or offlineOnline (continuous replication)Online (full load + CDC)Online (over network)Offline (shipped device)
Keeps source live during move?Yes (block-level replication)Yes (source stays operational)Yes (read from source)N/A (one-time bulk copy)
Cutover / sync mechanismTest + cutover instances, post-launch actionsCDC keeps target in sync until flipScheduled incremental re-syncSingle round trip; re-sync deltas online
Pick it whenLift-and-shift many servers fastDB engine change or DB rehost with min downtimeRecurring/large online file transferToo much data for the available bandwidth

Decision tree

What are you moving?(after picking the 7-R strategy)Whole serversA databaseFiles / objectsMGN (rehost)agent, block-level replication;test then cutover, post-launchactions; source stays liveDifferent DB engineon the target?Yes (heterogeneous)No (homogeneous)SCT + DMSSCT converts schema/code,DMS full load + CDC(near-zero downtime)DMS onlyno SCT needed;full load + CDC; sourcestays operationalBandwidth enough totransfer in the window?Yes (online)No (offline)Must keep partnerSFTP/FTPS/AS2?YesNoTransfer Familymanaged SFTP/FTPS/FTP/AS2into S3 / EFS; clients unchangedDataSynconline, validated, incremental;NFS/SMB/HDFS/object <-> AWSSnow Familyoffline; 210 TBper device;no SnowmobileAlways: retire / retain workloads need no tool; carry migration trafficover Direct Connect (sustained) or Site-to-Site VPN (quick).MGN test launch + still-running source = your rollback path.Re-architect into containers/serverless/purpose-built DBs is a separate decision (modernization).Snowmobile is retired: for multi-PB use Snowball Edge fleets, Direct Connect, or DataSync.
Cheat sheet

Cheat sheet

  • 7 Rs name the strategy; tools execute it
  • Rehost vs relocate vs replatform vs refactor
  • MGN is the primary rehost service
  • MGN uses continuous block-level replication to staging
  • MGN test launch then cutover then post-launch actions
  • MGN launch template controls the migrated instance
  • Homogeneous DB migration = DMS only, no SCT
  • Heterogeneous DB migration = SCT first, then DMS
  • DMS keeps the source database operational
  • DMS CDC enables near-zero-downtime cutover
  • DMS Serverless auto-scales migration capacity
  • DMS encrypts at rest with KMS, in flight with SSL
  • DataSync is the online file/object transfer service
  • DataSync needs an on-prem agent (not AWS-to-AWS)
  • Transfer Family keeps SFTP/FTPS/FTP/AS2 partner workflows
  • Snowball Edge Storage Optimized = 210 TB usable
  • Snowmobile is retired. Use Snow fleets, DX, or DataSync
  • VM Import/Export imports VM images as AMIs
  • Direct Connect vs VPN vs S3 Transfer Acceleration for migration
  • MGN post-launch actions automate and gate post-cutover validation
  • MGN cutover: replication continues until you finalize, then stops
  • DMS LOB modes trade speed for completeness. Inline avoids truncation
  • DMS CDC requires engine-specific source logging be enabled first
  • SCT extension pack emulates source DB features SCT can't convert
  • DataSync writes directly to the target S3 storage class
  • VMware HCX: vMotion/RAV for zero downtime, Bulk for parallel reboot
  • VMware Cloud on AWS DR uses pilot-light SRM/VCDR; stretched cluster for zero RPO

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References

  1. What is AWS Application Migration Service?
  2. What is AWS Database Migration Service?
  3. What is the AWS Schema Conversion Tool?
  4. What is AWS DataSync?
  5. What is AWS Transfer Family?
  6. AWS Snowball Edge device hardware information
  7. AWS Direct Connect
  8. AWS Site-to-Site VPN
  9. Migration strategies: the 7 Rs
  10. AWS Snowball Edge device hardware information