avatarEkant Mate (AWS APN Ambassador)

Summarize

Disaster Recovery(DR) Checklist

Disaster recovery, often abbreviated as DR, is a critical component of any organization’s IT strategy. It encompasses a set of policies, procedures, and tools to enable the recovery or continuation of technology infrastructure and systems following a natural or human-induced disaster.

In today’s fast-paced and interconnected digital world, where businesses rely heavily on data and IT systems, a robust disaster recovery plan is paramount. AWS (Amazon Web Services) offers a range of services and solutions to help organizations implement effective disaster recovery strategies that ensure business continuity.

Understanding Disaster Recovery in AWS

Disaster recovery, in the context of AWS, involves safeguarding your IT systems and data against various risks such as hardware failures, data corruption, natural disasters, cyber-attacks, and more. The ultimate goal is to minimize downtime, protect data integrity, and ensure the smooth operation of critical applications and services in the face of adversity.

Disaster recovery refers to the policies and procedures in place to recover critical IT infrastructure and data in case of a catastrophe. The goal is to minimize downtime and data loss.

Key elements of a DR strategy include:

  • Backups — Regular backups of data and servers, stored offsite.
  • Redundancy — Infrastructure spread across multiple Availability Zones/Regions.
  • Failover — Ability to quickly switch over to DR site/hardware.
  • Testing — Regularly testing failover process end-to-end.

DR on AWS

AWS provides building blocks and services to enable a robust DR strategy:

AWS Regions and Availability Zones — AWS infrastructure is hosted in fully isolated Regions and Availability Zones. This geographic redundancy helps protect from region-wide outages.

Scalability — Server infrastructure can scale up and down on demand to handle workload fluctuations and failovers.

Elastic Load Balancing — Load balancers distribute traffic across AZs and auto replace unhealthy instances.

Snapshots — Point-in-time snapshots of data volumes, databases, services. Stored redundantly across AZs.

AMIs — Replicate and launch server images across AZs and regions.

Versioning — Versioning on S3 objects helps recover from accidental deletes or corruptions.

Cross-Region Replication — Asynchronous copying of data between regions.

High Availability — Services like RDS provide failover between AZs to minimize downtime.

DR Scenarios on AWS

Here are some common DR scenarios and how AWS services can be used:

Backup and restore — Leverage EBS, RDS, DynamoDB snapshots to restore data. Use Data Pipeline for managing backup workflows.

The “backup and restore” approach is an effective method for guarding against data loss or corruption. This strategy is not only suitable for data protection but can also serve as a defense against regional disasters or the absence of redundancy for workloads confined to a single Availability Zone.

When implementing the backup and restore approach, it’s crucial not only to replicate data but also to recreate the infrastructure, configurations, and application code in a designated recovery Region. To ensure a swift and error-free redeployment of infrastructure, it’s highly advisable to utilize Infrastructure as Code (IaC) techniques, such as AWS CloudFormation or the AWS Cloud Development Kit (AWS CDK). Employing IaC is essential as it simplifies the restoration process in the recovery Region, reducing recovery times and ensuring compliance with your Recovery Time Objective (RTO).

Backup and Restore Architecture Diagram

In addition to safeguarding user data, it’s equally important to back up code and configurations, including Amazon Machine Images (AMIs) used for Amazon EC2 instances. Automating the redeployment of application code and configurations can be efficiently managed with AWS CodePipeline. This comprehensive approach ensures a quicker, more reliable recovery process in case of data loss or regional disasters.

Services used in backup and restore.

Restoring and testing backups

Any data stored in the disaster recovery Region as backups must be restored at time of failover. AWS Backup offers restore capability, but does not currently enable scheduled or automatic restoration. You can implement automatic restore to the DR region using the AWS SDK to call APIs for AWS Backup. You can set this up as a regularly recurring job or trigger restoration whenever a backup is completed. The following figure shows an example of automatic restoration using Amazon Simple Notification Service (Amazon SNS) and AWS Lambda. Implementing a scheduled periodic data restore is a good idea as data restore from backup is a control plane operation. If this operation was not available during a disaster, you would still have operable data stores created from a recent backup.

Pilot Light — Small version of app is always running in DR region. Scale up as needed for failover.

Using the “pilot light” approach in disaster recovery, you duplicate your data from one AWS Region to another and set up a replica of your essential workload infrastructure. Certain resources required for data replication and backup, like databases and object storage, are kept running at all times. However, components such as application servers remain in a “switched off” state. These servers are configured with the necessary application code but are not actively running. They are only powered up when testing or when you need to activate the disaster recovery failover.

Pilot Light Architecture Diagram

One advantage of the cloud is its flexibility, allowing you to deprovision resources when they’re not in use and provision them when necessary. A recommended practice for “switched off” resources is to refrain from deploying them initially and instead create the configurations and capabilities to deploy them (“switch on”) when the need arises. Unlike the backup and restore approach, the core infrastructure remains accessible at all times, providing the option to swiftly activate a full-scale production environment by powering on and scaling out your application servers.

Services used in Pilot Light in addition to backup and restore:

AWS Elastic Disaster Recovery

Pilot light Architecture Diagram

AWS Elastic Disaster Recovery (DRS) is a solution that continuously replicates server-hosted applications and databases to AWS, providing disaster recovery capabilities. It allows you to designate an AWS Region as a disaster recovery target for on-premises or other cloud-hosted workloads. This approach, referred to as the Pilot Light strategy, keeps a copy of data and dormant resources in an Amazon Virtual Private Cloud (Amazon VPC) acting as a staging area.

In the event of a failover, these staged resources are automatically utilized to create a fully functional deployment in the designated Amazon VPC, serving as the recovery location. This ensures a seamless recovery process for your applications and databases.

Warm Standby — Full scale mirrored environment in DR region, synchronization ongoing.

The warm standby approach takes the pilot light concept a step further by maintaining a scaled-down yet fully operational replica of your production environment in a different AWS Region. Unlike the pilot light strategy, this approach keeps your workload in the standby Region always operational. This setup reduces the time needed for recovery in case of a disaster.

Warm Standby Architecture Diagram

Moreover, the warm standby approach provides the flexibility to conduct regular testing and continuous testing to enhance your confidence in the disaster recovery process. This means you can ensure a swift and reliable recovery if the need arises.

Services used in Warm Standby:

All of the AWS services covered under backup and restore and pilot light are also used in warm standby for data backup, data replication, active/passive traffic routing, and deployment of infrastructure including EC2 instances.

Ensure that service quotas in your DR Region are set high enough so as to not limit you from scaling up to production capacity

Multi-Site — Active-active with multiple regions. Route 53 redirects traffic based on health checks.

You have a few options for running your workload in multiple AWS Regions when it comes to disaster recovery. The most complex and costly approach is the multi-site active/active strategy, where your workload serves traffic from all the Regions it’s deployed in. This approach offers near-zero recovery time for most disasters, provided you make the right technology choices and implementations. However, in cases of data corruption, you may still rely on backups, resulting in a non-zero recovery point.

Multi-site Architecture Diagram

On the other hand, the hot standby approach operates in an active/passive configuration. Users are directed to a single region, while the other Region(s) are reserved for disaster recovery and do not handle traffic. If you’re planning to set up a full environment in the second Region and want to maximize usage, active/active is the way to go. Alternatively, if you don’t need both Regions for user traffic, the warm standby approach is a more cost-effective and operationally simpler choice.

Services used :

All of the AWS services covered under backup and restore, pilot light, and warm standby also are used here for point-in-time data backup, data replication, active/active traffic routing, and deployment and scaling of infrastructure including EC2 instances.

Lets move on to checklist before implementation:

Checklist before implementing Disaster Recovery (DR) in AWS:

Checklist while implementing Disaster Recovery (DR) in AWS:

Checklist after implementing Disaster Recovery (DR) in AWS:

Conclusion

Disaster recovery is a critical aspect of modern business operations, and AWS provides a comprehensive set of tools and services to ensure business continuity even in the face of adversity. By following best practices, assessing your organization’s needs, and leveraging AWS’s capabilities, you can establish an effective disaster recovery plan that safeguards your data, applications, and, ultimately, your business.

AWS provides a flexible set of disaster recovery capabilities to achieve business continuity and uptime requirements. By utilizing the global infrastructure and managed services, companies can often achieve DR at lower costs compared to traditional models. Appropriate DR architecture depends on recovery objectives, costs and workload specifics. With regular testing, organizations can feel confident their critical workloads have failover capabilities built-in.

A well-prepared Disaster Recovery (DR) checklist is a crucial tool for safeguarding your organization’s data and operations. By following a structured DR checklist, you can systematically plan, implement, and maintain your DR strategy.

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