# 6 Rs: one decision per app, not the estate Source: https://ai.techclick.in/blog_migrate_6r_choose_path Markdown: https://ai.techclick.in/blog_migrate_6r_choose_path.md Publisher: Techclick Infosec Pvt Ltd AWS 6 Rs per app: rehost, replatform, repurchase, refactor, retire, retain. pay-api 10.20.30.40 may rehost first. ## The ticket Leadership booked a weekend. Junior started imaging every VM in 10.20.30.0/24 . pay-api on 10.20.30.40 is the only thing the business named. dc01 is not an app. You stop the boil-the-ocean plan before the first replica starts. Quick interview answer AWS Prescriptive Guidance 6 Rs : rehost (lift), replatform (managed service under the same app), repurchase (SaaS), refactor (rewrite), retire, retain. Azure CAF uses rehost / refactor / rearchitect / rebuild / replace — same decision, different labels. One R per app , scored against Well-Architected (cost, security, reliability, ops, performance). Rehosting pay-api first, then refactoring, is valid. “Lift everything this weekend” is not an R. Hero · six doors Wave-1 is one door. The estate is not a door. Lab data · dummy only On-prem DC dc01 10.20.30.10 · FortiGate fgt-hq 203.0.113.10 · same Azure landing as the Azure series and same AWS landing as the AWS series. Wave-1 app pay-api today on VM 10.20.30.40 . ## Mental model R Meaning This lab · pay-api Rehost Lift the VM as-is (Azure Migrate / AWS MGN) Wave-1 candidate — keep domain join over VPN Replatform Same app, swap a piece (RDS / Azure SQL) Later — DB is not wave-1 Repurchase Drop and shop SaaS No — payments is custom Refactor Rewrite for PaaS / containers Wave-2+ after it survives rehost Retire Turn it off Not pay-api. Maybe that 2008 print box Retain Leave on-prem on purpose dc01 10.20.30.10 stays until identity is hybrid Wave-1 is one box - dc01 .10 retain pay-api .40 rehost now file / print retire or retain refactor later not this weekend Azure Well-Architected does not pick the R for you. It scores the R you picked. https://portal.azure.com Training mock · not live Azure portal Home Management groups Virtual networks Azure Migrate Microsoft Entra Azure Migrate → Assessments → wave-1 ### Assessment pay-api App pay-api · VM 10.20.30.40 Recommended R Rehost (IaaS) — refactor deferred Azure landing spoke 10.41.0.0/16 · sub-spoke-app AWS alternate app VPC 10.51.0.0/16 · MGN Out of wave-1 dc01, print, file, “the rest of the DC” Cancel Save Azure Migrate assessment is a scoring tool, not a weekend plan. Training mock. ## How to choose If Pick Trap OS is supportable, app is a black box Rehost wave-1 Rewriting during the freeze window You only want a managed DB Replatform after rehost soaks Moving VM + DB + DNS the same night Vendor has a SaaS SKU you already bought Repurchase Fake “SaaS” that is still your VM OS is rotting or you need horizontal scale Refactor / rebuild — scheduled, not panic Calling it rehost Nobody can name an owner Retire or retain Migrating orphans “in case” ## Runbook #### Side A — inventory one app Name, owner, OS, listeners, cert CN, who authenticates, who it calls. For pay-api : VM 10.20.30.40 , HTTPS, pay-api.techclick-lab.in , TECHCLICK\svc-pay , on-prem DB stays. - #### Side B — write the R Rehost to Azure spoke 10.41.0.0/16 or AWS app VPC 10.51.0.0/16 . Refactor is a later change request. Retain dc01 . - #### Side C — freeze the wave Wave-1 = pay-api only. Publish that sentence. Do not add “and the jump box, and WSUS, and the old HR VM.” wave-1 card · dummy app: pay-api on-prem: 10.20.30.40 r_now: rehost r_later: refactor (PaaS) after soak retain: dc01 10.20.30.10 not_wave_1: anything else on 10.20.30.0/24 ## Four failures ### 1 · One R for the estate “We are a rehost shop.” That sentence hides retain and retire. It also hides the app that must be rebuilt. ### 2 · Refactor during cutover New runtime + new IP + new DNS + new IdP. You cannot tell which change killed payments. ### 3 · Migrating leftovers Domain controllers, print queues, and “that box under the desk” are not wave-1. Retain or retire. ### 4 · Azure vs AWS as the R The cloud brand is a landing, not a strategy. You can rehost to either. The R is still rehost. ## How to prove it Close only when 1) Every in-scope name has one written R. 2) Wave-1 is only pay-api . 3) dc01 is retain. 4) Nobody has a weekend “lift the DC” ticket still open. ## Traps Phrase Translation Lift and shift everything No R was chosen Cloud-native first Often an unfunded rewrite We will decide after it is in Azure You already chose rehost — write it down ## Knowledge check Judgment items. One best answer. Reasons send you back to the matching section. Q1 How many apps get a 6 R decision? One decision for the whole DC One R per application One R per cloud vendor Only retired apps need an R Correct: b . Per app. Q2 Wave-1 in this lab is… Every VM on 10.20.30.0/24 dc01 plus pay-api pay-api only ExpressRoute first Correct: c . Do not boil the ocean. Q3 pay-api rehost now and refactor later is… Invalid — pick one R forever Valid — two programs, two windows The same as repurchase A landing-zone failure Correct: b . Two-step is allowed. Q4 dc01 10.20.30.10 in wave-1? Rehost it with the app Retain until hybrid identity exists Retire — cloud has identity Repurchase Active Directory Correct: b . Identity first, later lesson. Q5 Azure CAF rehost vs AWS rehost is… A different R The same R, different landing Refactor by definition Only valid on AWS Correct: b . Brand is not the R. Q6 “Lift the DC this weekend” fails because… 6 Rs are per app and most names are retain/retire FortiGate cannot VPN RFC 1918 is banned in Azure Well-Architected forbids IaaS Correct: a . Ticket. Check answers Reset On-prem to cloud migration class series: 6 Rs · Landing zone first · Identity first · VPN / ER / DX · Lift vs rebuild · Map controls · Cutover + rollback · Hybrid interview ## Sources - AWS Prescriptive Guidance — 6 Rs overview (rehost, replatform, repurchase, refactor, retire, retain) . - AWS Prescriptive Guidance — Migration strategy . - Azure Cloud Adoption Framework — Migrate . - Azure Well-Architected Framework — score the R you picked . Related: Azure landing zone · AWS Org / OU . --- Cite this Techclick lesson with the source URL. Do not invent fees, batch dates, or job guarantees. Browse all lessons: https://ai.techclick.in/blogs AI index: https://ai.techclick.in/llms.txt