Disaster Recovery

• Disaster: any event that has a negative impact on a company’s business continuity or finances
• Disaster Recovery (DR) is about preparing for and recovering from a disaster
• Disaster recovery solutions:
  • On-premise to on-premise: traditional DR, expensive
  • On-premise to cloud: hybrid recovery
  • AWS Cloud Region A to AWS Cloud Region B

RPO and RTO

• RPO - Recovery Point Objective: How often we create backups. Time between the RPO and the disaster is the data loss
• RTO - Recovery Time Objective: The point in time when the recovery finishes. The time between the disaster and the RTO is downtime

Disaster Recovery Strategies

• Backup and Restore: high RPO, cheap, easy to manage and accomplish
• Pilot Light:
  • A small version of the app is always running in the cloud
  • Useful for critical core (pilot light)
  • Similar to backup and restore strategy
  • Faster than backup and restore as critical system are already running
• Warm Standby
  • Full system is up and running but at a minimal size
  • Upon disaster we can scale to production load
• Hot Site / Multi Site Approach
  • Very low RTO - very expensive
  • Full production scale is running on the cloud
• All AWS Multi Region

Disaster Recovery Tips

• Backups:
  • EBS Snapshots, RDS, automated backups, snapshots, etc.
  • Regular pushes to S3/S3 IA/Glacier, Lifecycle Policy, Cross region replication
  • From on-premise: Snowball or Storage Gateway
• High Availability:
  • Use Route53 to migrate DNS over from region to region
  • RDS Multi-AZ, ElastiCache Multi-AZ, EFS, S3
  • Site to site VPN as recovery from Direct Connect
• Replication:
  • RDS Replication (Cross Region), AWS Aurora + Global Databases
  • Database replication from on-premise to RDS
  • Storage Gateway
• Automation:
  • CloudFormation/Elastic Beanstalk to recreate a whole new environment
  • Recover/Reboot EC2 instances with CloudWatch if alarm is in fail state (ALARM)
  • AWS Lambda for customized automation
• Chaos
  • Netflix has a “simian-army” randomly terminating EC2 instances

On-Premise Strategy with AWS

• Ability to download Amazon Linux 2 AMI as a VIM (iso format)
• VM Import/Export:
  • Ability to migrate existing applications into EC2
  • Ability to create a DR repository for on-premise VMs
  • Ability to export back the VMs form EC2 to on-premise
• AWS Application Discovery Service:
  • Gather information about on-premise servers to plan a migration
  • Provides information about server utilization and dependency mappings
  • Track all migrations with AWS Migration Hub
• AWS Database Migration Service (DMS)
• AWS Server Migration Service (SMS):
  • Incremental replication of on-premise live servers to AWS