As you prepare for the AWS Certified Solutions Architect – Associate (SAA-C03) exam, one key area for study is disaster recovery (DR) strategies. Understanding these strategies, their various characteristics, and use cases, can provide you with the knowledge you need to plan, manage, and recover from disruptions effectively.
I. Backup and Restore
Backup and restore is the simplest DR strategy. Data and applications are periodically backed up to a secondary location, which could be an offsite facility or a cloud-based solution like Amazon S3. In the event of a disaster, these backups are restored to the active system.
Amazon S3, for instance, allows you to back up and restore your data with its Versioning capability. Any backup is just a version of your object, which can be easily restored when necessary. Glacier, another AWS service, is used for long-term backup.
The main drawback of this strategy is recovery time, as it can take a while to restore data or applications to the active system. Thus, it is most suitable for non-critical applications or data.
II. Pilot Light
The pilot light strategy is essentially an improvement on the backup and restore approach. Essentially, a replica of your core systems (the ‘pilot light’) is always running in the cloud. In a disaster, you rapidly provision and scale up that system to take over from your primary system.
This strategy reduces recovery time, as the disruption is smaller and data is readily accessible. However, it can be more expensive than a backup and restore strategy, as you have to pay for the pilot light resources. But with AWS services like RDS and EC2, you can keep your core systems as sleep mode (example, EC2 in stop mode or RDS in pause mode) and in the event of DR, you can make it live immediately.
III. Warm Standby
A warm standby is a step up from the pilot light in terms of availability and recovery time. In this mode, a duplicate version of your primary system is constantly running in the cloud. The system is ‘warm’, meaning it’s on and working, but it’s not handling live traffic until a disaster occurs.
The advantages include low recovery time and high availability. The downside is the cost, as you are effectively running two systems in parallel. AWS Auto Scaling is a key service for implementing warm standbys, allowing you to scale up or down based on demand conditions.
IV. Active-Active Failover
Active-Active Failover is the most powerful DR strategy. In this model, your workload is distributed across two or more similar production environments, typically in different geographic locations. All are processing live transactions, but if a disaster occurs in one location, the other locations take up the load.
Active-Active Failover supports the highest degree of availability but is also the most expensive. Its implementation on AWS would typically involve Multi-AZ deployments, Elastic Load Balancing, and Route53 for DNS failover.
V. Recovery Point Objective (RPO) and Recovery Time Objective (RTO)
RPO and RTO are key metrics used in disaster recovery planning. RPO is the maximum acceptable amount of data loss measured in time, while RTO is the duration of time and a service level within which a business process must be restored after a disaster in order to avoid unacceptable consequences.
To achieve the desired RPO and RTO, your choice of DR strategy will depend on many factors including the nature of your data and applications, your organization’s needs, budget, and many others. AWS provides the tools and services you need to implement any of these DR strategies effectively, making your preparation for the AWS Certified Solutions Architect – Associate (SAA-C03) exam invaluable for your role as a solutions architect.
Keep in mind that being effective with these DR strategies not only requires knowledge of the strategies themselves, but also a deep understanding of how to use AWS services to implement them.
Practice Test
True or False: The Active-Active failover disaster recovery strategy entails running a duplicate system in a separate physical location that is live and available to take over if the primary system goes offline.
- True
- False
Answer: True
Explanation: In an Active-Active failover, both systems always run and share the load. If one system fails, the other continues to function with the full workload.
In the context of disaster recovery, RPO determines the maximum amount of data loss acceptable measured in time. For example, if the RPO is 4 hours, the data might be lost up to the last four hours. Is this statement correct?
- True
- False
Answer: True
Explanation: RPO stands for Recovery Point Objective. It signifies the maximum acceptable amount of data loss, measured in units of time, in the event of a disaster.
Multiple select: Which of the following are Disaster Recovery Strategies in AWS?
- a. Backup and Restore
- b. Pilot Light
- c. Warm Standby
- d. Cold Standby
- e. Active-Active Failover
Answer: a, b, c, e
Explanation: All except option d, Cold Standby, are renowned strategies employed for Disaster Recovery in AWS.
Single select: What does the RTO refer to?
- a. Recovery Time Objective
- b. Recovery Test Objective
- c. Recovery Team Objective
- d. Recovery Trend Objective
Answer: a. Recovery Time Objective
Explanation: RTO stands for Recovery Time Objective; it represents the acceptable amount of time that can pass before system recovery after an outage.
True or False: Warm standby is a DR strategy that involves a redundant and inactive system.
- True
- False
Answer: False
Explanation: Warm standby involves a system that is redundant and active but is not handling live traffic unless a disaster happens.
Single-select: In which DR strategy the redundant system remains off and only turned on if the main system fails?
- a. Active-Active Failover
- b. Active-Passive Failover
- c. Warm Standby
- d. Recovery Point Objective (RPO)
Answer: b. Active-Passive Failover
Explanation: In the Active-Passive Failover DR strategy, a secondary (redundant) system is available and is only turned on if the main system fails.
True or False: Backup and Restore is a Reactive Disaster Recovery strategy.
- True
- False
Answer: True
Explanation: Yes, Backup and Restore is indeed a Reactive Disaster Recovery strategy as the response occurs after the disaster has occurred.
Multiple select: Which of the following are components of a comprehensive disaster recovery strategy?
- a. Identifying the digital assets to protect
- b. Regular testing and documentation
- c. Defining RPO and RTO
- d. Ignoring cost-effectiveness
Answer: a, b, c
Explanation: A comprehensive disaster recovery strategy includes identifying digital assets, regular testing and documentation, and defining RPO and RTO. However, considering cost-effectiveness is crucial to ensure a feasible strategy.
True or False: An important benefit of the Pilot Light strategy is that it minimizes downtime because data replication and syncing occurs in real-time.
- True
- False
Answer: True
Explanation: The Pilot Light strategy does involve real-time data replication and syncing, thus minimizing downtime in the event of a disaster.
Single select: What disaster recovery strategy provides the lowest RTO?
- a. Active-Active
- b. Backup and Restore
- c. Pilot Light
- d. Warm Standby
Answer: a. Active-Active
Explanation: The Active-Active configuration provides the lowest RTO, as there is no need to “spin up” systems because the systems are already running and are instantly available at all times.
Multiple select: Which of the following can improve RPO?
- a. Frequent Backups
- b. Continuous Data Replication
- c. Reducing the amount of data
- d. Increasing the amount of data
Answer: a, b, c
Explanation: Frequent backups and continuous data replication can reduce data loss thereby, improving RPO. Reducing the amount of data also has the potential to improve RPO, contrary to increasing the data.
Interview Questions
What is the main purpose of Disaster Recovery (DR) in AWS?
The main purpose of Disaster Recovery in AWS is to enable a quick and smooth recovery of data and IT infrastructure by retaining all or backup copies of data in AWS after a natural or man-made catastrophe.
What is meant by Recovery Point Objective (RPO)?
Recovery Point Objective (RPO) is a measure of the maximum targeted period in which data might be lost due to a major incident. An RPO is determined based on the amount of data that a business can afford to lose before it impacts business continuity.
Define Recovery Time Objective (RTO).
Recovery Time Objective (RTO) is the targeted duration of time and a service level within which a business process must be restored after a disaster in order to avoid unacceptable consequences associated with a break in business continuity.
What is a Pilot Light Disaster Recovery strategy in AWS?
The term Pilot Light refers to a DR scenario where a minimal version of an environment is always running in the cloud. This approach significantly reduces the recovery time because there is no need to start the system from scratch in the aftermath of a disaster.
What is Warm Standby DR strategy in AWS?
In a Warm Standby DR scenario, a scaled-down version of a fully functional environment is always running in the cloud. It allows for quick failover during a disaster event by quickly scaling up to handle the production load.
What does an Active-Active Failover strategy refer to in AWS?
An Active-Active Failover strategy refers to a DR approach where your workload is distributed across multiple active systems in different regions. This ensures there is no single point of failure and promotes uninterrupted business operations even if a disaster strikes one of the geographical regions.
How is the backup and restore strategy used in AWS for disaster recovery?
The backup and restore strategy works by regularly backing up data from the primary data center and restoring it on the AWS platform. With AWS’s storage and database services, organizations can easily save their data in a secure and durable manner.
What is the role of Amazon S3 in AWS DR strategies?
Amazon S3 plays a significant role in DR strategies by providing a scalable, secure, and durable storage at low costs. It allows easy backup, restore, and archiving of data.
What is the significance of the Amazon RDS Snapshot in a DR strategy?
Amazon RDS Snapshot allows to backup a relational database service, which plays a crucial role in DR strategy. It allows for automated backups of databases according to the set scheduled time and retains these backups for a specified period.
Can we automate the failover process in AWS? How?
Yes, AWS Route 53 can be used to automate the failover process. By using health checks and DNS failover, Route 53 can automatically route traffic from an unhealthy resource to a healthy resource.
How does Amazon CloudWatch help in a DR strategy?
Amazon CloudWatch helps in DR strategy by providing monitoring for AWS resources and applications. It provides actionable insights through metrics and logs to understand system health and performance which can be crucial during and after a disaster event.
How do you ensure data security during disaster recovery operations in AWS?
Data security during DR operations can be ensured by implementing AWS security features like Identity and Access Management (IAM) for secure access, AWS Key Management Service (KMS) for encryption, and Security Groups and Network Access Control Lists (ACLs) for network security.
How does AWS Auto Scaling aid in disaster recovery?
AWS Auto Scaling helps in disaster recovery by automatically adjusting capacity to maintain steady, predictable performance at the lowest cost. It allows to scale up for handling the failover traffic and scale down when the disaster is resolved.
Can Elastic Load Balancing be used in a DR strategy in AWS?
Yes, Elastic Load Balancing automatically distributes incoming application traffic across multiple targets ensuring high availability and fault tolerance in applications. It plays a crucial role, especially in Active-Active Failover disaster recovery strategy.
What is AWS’s Glacier, and how does it support in Disaster Recovery strategies?
AWS Glacier is a secure, durable, and low-cost storage class for data archiving and long-term backup. It provides comprehensive security and compliance capabilities and supports specific regulatory requirements, making it a perfect choice for long-term disaster recovery storage.
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