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Disaster Recovery Testing & Drills: How do I know my plan works?

How to ensure reliability with Disaster Recovery testing
Disaster recovery testing is essential to any DR plan, enabling you to identify and address potential issues before they become real problems
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Natural disasters, cyber attacks, system failures, and even human error can strike at any moment.  These put your organization’s critical applications at risk. Having a well-crafted disaster recovery plan can differentiate between a quick, safe recovery or prolonged downtime and business continuity risks that can cost your organization millions. But how would you know if your disaster recovery plan works?

Regular disaster recovery testing and drills are essential to any disaster recovery plan, enabling you to identify and address potential issues before they become actual problems. It is important to plan and execute testing and drills properly, or you might get a false sense of security while not being protected at all.

To ensure that your disaster recovery plan is effective, you must develop a comprehensive testing and drill strategy that covers all the critical components of your infrastructure, applications, and processes. You also need to ensure that your testing and drill processes are well-documented, repeatable, realistic, and reflect real-world scenarios that could impact your operations.

This article discusses the steps you can take to design, execute, and evaluate disaster recovery testing and drills.

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Why Disaster Recovery Testing is Critical

Recovery Challenges for Distributed Systems

In well-architected distributed systems, the failure of one component should not mean total system failure. Rather, the failure should be isolated to the component itself. It is possible to design systems to detect and respond to these kinds of failures appropriately. Either way, a disaster recovery test plan must take these nuances into account so that realistic conditions are being exercised. Here are some challenges that must be addressed when designing a recoverable distributed system:

Network Failure and Data Replication

The network topology can change during normal operation. Network partitioning, network congestion, policies, rules, security groups, and many other factors can cause an intermittent or permanent disconnection between components in the system.

How are you designing and operating your primary and recovery network in the case of failover? It’s also important to understand how you can test in parallel to a production system. A recovery system is only good if we know we can recover it on-demand.

Distributed Transaction Management

Transactions performed in a distributed system may span multiple systems, meaning they must be coordinated across those systems. This coordination is not trivial because it involves coordinating transactions across multiple machine processes. 

In addition, transactions may need to coordinate with other transactions on those other machines and external resources such as databases or file systems.

Service Dependency Resolution

Services need to be able to find each other to collaborate on business logic execution or service calls between them. Most microservices implementations require service discovery; however, it also has applications in monolithic architectures.

Data Consistency and Recovery

In most cases, disaster recovery aims to restore service as quickly as possible while minimizing data loss or corruption. Therefore, applications must be designed to recover from failures without losing their state or corrupting their data.

Backup and Disaster Recovery Planning

Backups are critical to any recovery plan and can be rebuilt from scratch if you don’t have a backup copy of your data.

Disaster Recovery Testing + Verification of Recovery Mechanisms

Recovery plans rely on complex mechanisms that need testing before being implemented in production environments. 

Testing must be done periodically because new software versions are always being released with new features that can affect recovery.

Dependencies and Setting Order of Recovery

If a distributed system fails, it can be hard to determine how it will be recovered since there may be many dependencies between the components or services. Here are some key considerations for managing dependencies and setting the order of recovery in a distributed system:

Identify critical dependencies: Start by mapping out the dependencies between different services and components in your system. Identify the dependencies most critical to your system’s functionality and determine the impact of failure on these dependencies.

Prioritize dependencies: Once you have identified critical dependencies, prioritize them based on their impact on system functionality and the extent to which other services or components depend on them.

Establish recovery procedures: Define recovery procedures for each service or component, specifying the steps required to recover them and the dependencies they rely on.  

Automate recovery processes: Consider automating the recovery processes wherever possible to minimize manual intervention and reduce the time required to recover the system.

Test and validate the recovery plan: Regularly test and validate it to ensure it remains effective and up-to-date. Conduct mock recovery exercises to identify potential issues and refine the plan.

Use Case Scenario Examples

Here are some of the use cases for data recovery:

Use-case #1 – Recovery of Data (AWS and Azure)

An organization stores its critical business data in the cloud using AWS and Azure services. A recent cyber attack has caused data corruption and loss, and the organization needs to recover the data as quickly as possible to avoid severe financial and reputational damage.

Steps for recovery:

  1. Identify the extent of data loss: Organizations should determine the extent and impact of data loss. This may involve analyzing server logs, monitoring systems, and user feedback to identify the scope of the issue.
  2. Initiate the data recovery process: The next step is to initiate the data recovery process. AWS and Azure offer different options for recovering data, including backup and restore, replication, and failover. The specific recovery strategy will depend on the nature of the data loss, the backup and recovery options available, and the organization’s recovery time objectives (RTO) and recovery point objectives (RPO).
  3. Restore data from backups: If backups are available, the organization can restore data from these backups. AWS and Azure offer backup and restore services that allow organizations to create and manage backup copies of their data. These services enable organizations to recover data quickly and easily during data loss. And with N2WS you can do this with the click of a button.
  4. Replicate data: If backups are unavailable or incomplete, the organization can replicate data from other sources. AWS and Azure offer replication services that enable organizations to replicate data across different regions and availability zones to ensure data availability and redundancy.
  5. Failover to secondary systems: If the primary systems are not recoverable, the organization can failover to secondary systems that are geographically dispersed and designed for high availability. AWS and Azure offer failover services that enable organizations to automatically switch to secondary systems in case of a primary system failure.
  6. Verify data integrity and consistency: After data recovery is complete, the organization must verify the integrity and consistency of the recovered data. This may involve running data consistency checks, comparing recovered data to backup copies, and validating the data against user feedback.
  7. Evaluate the recovery process: After the recovery process is complete, the organization should evaluate the recovery process to identify areas for improvement. This may involve conducting post-mortem reviews, analyzing recovery metrics, and updating the disaster recovery plan to incorporate lessons learned.

Use-Case #2 – Recovery of a Complex App Made Up of Multiple Services (Compute, Data, Networking)

An organization’s mission-critical application, composed of multiple services such as computing, data, and networking, has experienced a catastrophic outage due to a natural disaster. The organization must recover the application quickly to minimize financial and reputational damage.

  1. Identify dependencies: The first step is to identify the dependencies between the various application services. This helps in determining the order in which the services are recovered.
  2. Start with computing services: The services should be the first to be recovered. This may involve starting up EC2 instances or Azure virtual machines and ensuring they are correctly configured with the necessary security groups, IAM roles, and network settings.
  3. Recover data services: Once the computing services are up and running, the next step is to recover the data services. This may involve recovering and restoring data from backups or replicating data from other sources, such as geographically dispersed secondary systems.
  4. Restore networking services: After the computer and data services are recovered, the networking services should be restored. This may involve configuring virtual private clouds (VPCs), subnets, and network security groups to ensure traffic flows directly between the various services.
  5. Test and verify: Once all the services have been recovered, the application should be tested to ensure it functions correctly. This may involve running automated tests or manual checks to verify that all the services communicate correctly and that the application performs as expected.
  6. Evaluate the recovery process: After the recovery process is complete, the organization should evaluate the recovery process to identify areas for improvement. This may involve conducting post-mortem reviews, analyzing recovery metrics, and updating the disaster recovery plan to incorporate lessons learned.

Automation is Not Desired. It’s Required

Today, IT systems are expected to be always available and to be recoverable in the event of a disruption. Traditional manual disaster recovery processes are time-consuming, prone to errors, and may not meet the RTOs and RPOs. Automation is a critical component of modern disaster recovery planning and is necessary to achieve RTOs and RPOs.

Automation can accelerate the process of recovery, eliminate errors, and increase control and visibility over the recovery procedure. With automated disaster recovery, IT teams can ensure the recovery process is consistent, reliable, and predictable, even in complex and dynamic IT environments.

Test The Plan, Don’t Plan The Test

A disaster recovery plan is only as effective as its implementation. To ensure that a disaster recovery plan will work when needed, it’s critical to test it regularly. Testing helps identify gaps and weaknesses in the plan, provides an opportunity to refine the plan based on lessons learned, and builds confidence in the recovery process.

It’s crucial to test the strategy in a situation that mimics the most likely forms of disruptions that might happen. All essential elements, such as hardware, software, networks, and data, should be tested, and all pertinent parties, such as IT employees, business units, and outside vendors, should be included.

The disaster recovery plan must be updated per the test findings analysis for testing to be effective. Organizations may ensure they are ready for any potential disaster and can quickly and effectively recover crucial IT systems and data quickly and effectively by periodically testing the plan.

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Final Words on Disaster Recovery Testing

A strong disaster recovery strategy must include testing and drills for disaster recovery. Organizations may strengthen their confidence in the recovery process, find and fix weaknesses in the plan, and ensure that vital IT systems and data can be recovered promptly and effectively during a disruption.

It is essential to remember that testing must be exhaustive and involve all relevant parties. The outcomes should be recorded, examined, and used to update the disaster recovery plan as required.

In the end, a tested and well-documented disaster recovery plan can assist firms in reducing the financial and reputational harm brought on by IT outages and guarantee business continuity in the event of a disaster.

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