6R migration

6 R's of Cloud Migration

https://aws.amazon.com/blogs/enterprise-strategy/6-strategies-for-migrating-applications-to-the-cloud/

Rehosting - Lift and Shift

• Migrate as it is (App Virtual Machine - EC2, DB => EC2)
• +Reduced Admin Overhead (IAAS)
• +Potentially easier to optmise when in AWS
• Cost savings -- burst instances
• not taking full advantage of cloud
• kicking the can down the road
• VM Import/Export & Server Migration Service

Replatforming - Lift and Shift with Optimization

• like rehosting but with Optimization
• using RDS instead of self-managed DBs
• using ELB instead of load balancers
• using S3 as backup or media storage
• no real negatives & no world-changing benefits
• Admin Overhead Reductions, Performance Benefits, more effective backups or Improved HA/FT - high availability & fault tolreant

Repurchasing - Move to something new.. SAAS

• when there is no reason to self-manage
  • USE a XaaS Product
• Example
  • MS Exchange => Microsoft 365
  • CRM => Salesforce
  • Payroll => Xero

Refactoring/ Re-architecting - Take advantage of cloud

• reviewing the architecture of an application
• adopting cloud-native architectures & products
• Service-Orientated or Microservices
• APIs, Event-Driven or Serverless
• Initially very expensive & time consuming
• best long-term benefits
  • often cheaper
  • much more scalable
  • better HA/FT
  • costs aligned with app usage

Retire - Do we even need this ? NO? Dump it

• Systems are often running for no reason
• Auditing their usage is often more work than leaving running
• If you dont need the application --> switch if off

Retain - Not worth time/money or is too scary to migrate

• DO NOTHING
• Old Application - not worth the move
• Complex application - leave till later
• Super critical application - risky
• Complete the migration - swing back to focus on the left-overs

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