Data recovery involves retrieving lost, corrupted, deleted, or inaccessible data from a storage medium. It particularly becomes necessary when a disaster strikes leading to loss or corruption of data.
In the context of AWS, data recovery generally pertains to restoring from backups, recovering from failure scenarios (instances, databases, disk failures, etc.), and setting up disaster recovery strategies.
AWS Services for Data Recovery
AWS S3
Amazon S3 offers versioning control to manage, retrieve, and restore every version of every object stored in your Amazon S3 buckets. This makes it easier to recover from both unintended user actions and application failures.
import boto3
s3 = boto3.resource('s3')
# get the latest version of the object
object = s3.ObjectVersion('my_bucket', 'hello.txt').get()
print(object.get())
# revert to an older version
for version in bucket.object_versions.filter(Prefix='hello.txt'):
if version.key == 'hello.txt':
version.delete()
This will revert the object to the previous version by deleting the latest version.
AWS RDS
Amazon RDS offers automated backups and database snapshots for reliable recovery. Automated backups allow recovery of your DB instance to any second during your retention period (up to the last five minutes), whereas database snapshots are user-initiated backups of your DB instance.
AWS Glacier
For long-term data archiving and backup, Amazon Glacier provides extremely low-cost storage. It is ideal for data that is accessed less frequently and can tolerate a retrieval time of a few hours.
Strategies for Data Recovery in AWS
Backup and Restore
AWS offers several services that facilitate backing up your data to the cloud and quickly restoring it.
Example Services: AWS Backup, Amazon S3, and AWS Snapshot
Pilot Light
The idea of the Pilot Light strategy is similar to a backup and restore strategy, where you maintain a minimum version of your environment always running. In the event of a disaster, you can rapidly provision a full-scale production environment around the critical core or “Pilot Light.”
Example Services: AWS CloudFormation, Amazon Route 53 (for DNS routing), and AWS Auto Scaling.
Warm Standby
A Warm Standby is a redundant version of a production environment. It extends the Pilot Light elements and preparation to include always-on, scaled-down versions of key elements of your systems.
Example Services: AWS CloudFormation, Amazon Route53, AWS Auto Scaling, and Amazon Elastic IP (to quickly remap address to the standby instance).
Data Recovery Planning
When planning for data recovery, consider these important aspects:
- Recovery Point Objective (RPO): It defines the amount of data loss an organization can tolerate.
- Recovery Time Objective (RTO): It defines the amount of time an application can be down without causing significant damage to the business.
A successful AWS data recovery strategy requires a collection of policies, tools, and procedures to enable the recovery or continuation of vital technology infrastructure and systems following a disaster. Therefore, making it an essential part of preparation for the AWS Certified Solutions Architect – Associate (SAA-C03) exam.
While AWS provides robust features and services to enable data recovery, it’s the responsibility of the architect to make the right choices and design a resilient, efficient, and cost-effective data recovery strategy using the tools provided. Understanding and applying these strategies is the key to ace questions related to data recovery in the AWS Certified Solutions Architect – Associate (SAA-C03) exam.
Practice Test
True/False: AWS provides the ability to recover data in case of a system failure or disaster.
- True
- False
Answer: True
Explanation: AWS offers a variety of services like S3 versioning, Glacier, and backup/restore functionality in RDS and EBS to recover data.
True/False: AWS does not support point-in-time recovery of data.
- True
- False
Answer: False
Explanation: AWS supports point-in-time recovery of data by maintaining continuous backups of your data.
Single Select: Which AWS service is used for creating automatic backups of Amazon RDS instances?
- A. AWS Backup
- B. Amazon S3
- C. AWS Glue
- D. Amazon Glacier
Answer: A. AWS Backup
Explanation: AWS Backup is a fully managed backup service that makes it easy to centralize and automate the backup of data across AWS services, including Amazon RDS instances.
True/False: Amazon RDS Automated Backup allows recovery of data to any point within the retention period.
- True
- False
Answer: True
Explanation: Amazon RDS Automated Backup allows you to recover your Database Instance to any second during your retention period, up to the last five minutes.
Single Select: Which is the cheapest storage class in Amazon S3 for data archival?
- A. S3 Standard
- B. S3 One Zone-IA
- C. S3 Glacier Deep Archive
- D. S3 Glacier
Answer: C. S3 Glacier Deep Archive
Explanation: S3 Glacier Deep Archive is the lowest-cost storage class and supports long-term retention and digital preservation for data that may be accessed once or twice in a year.
Multiple Select: Which of the following AWS services support backups?
- A. Amazon EC2
- B. Amazon S3
- C. AWS Lambda
- D. Amazon DynamoDB
Answer: A. Amazon EC2, B. Amazon S3, D. Amazon DynamoDB
Explanation: All these services including Amazon EC2, Amazon S3, and Amazon DynamoDB support backups, for data protection and recovery.
True/False: AWS is responsible for data recovery in a shared responsibility model.
- True
- False
Answer: False
Explanation: According to the AWS shared responsibility model, AWS is responsible for the security of the cloud, while customers are responsible for the security in the cloud, including data recovery.
Single Select: Recovery point objective (RPO) in AWS refers to…
- A. The amount of data lost if a restore is necessary
- B. The maximum allowed downtime
- C. The target time for data recovery
- D. The frequency of backups
Answer: A. The amount of data lost if a restore is necessary
Explanation: RPO is the maximum acceptable amount of data loss measured in time. It refers to the amount of data that could be lost before the loss significantly harms business.
Multiple Select: What are the two methods to restore Amazon RDS instances?
- A. Point-in-time recovery
- B. Snapshot restore
- C. Cryptographic hash function
- D. Network firewall
Answer: A. Point-in-time recovery, B. Snapshot restore
Explanation: You can restore Amazon RDS instances by performing a point-in-time recovery or by restoring a DB snapshot.
True/False: In AWS, data backups can be retained indefinitely.
- True
- False
Answer: True
Explanation: AWS allows the retention of backups indefinitely. However, it’s important to manage and clean up backup resources to reduce costs.
Interview Questions
What does AWS provide to support data recovery and business continuity?
AWS provides a set of cloud-based disaster recovery services, including storage services like Elastic Block Store (EBS), Simple Storage Service (S3), Glacier for archival storage, as well as database services such as RDS, DynamoDB. Services like EC2 and Elastic Beanstalk also provide capabilities to quickly provision and scale applications.
How can you backup data stored in an Amazon S3 bucket?
You can configure cross-region replication (CRR) to automatically replicate every object uploaded to your S3 bucket to a destination bucket located in a different AWS region.
What AWS service would you use for long term, archival data storage?
For long term, archival data storage, Amazon Glacier would be the appropriate AWS service.
How can you ensure high durability of data stored in Amazon S3?
Amazon S3 automatically replicates data across at least three physical facilities in an AWS region which provides 99.999999999% durability.
In the context of AWS, what is the purpose of EBS Snapshots?
EBS snapshots are backups of your EBS volumes. They are stored in Amazon S3 and provide point-in-time recovery of your volumes.
How does RDS Multi-AZ deployment contribute to data recovery?
In a multi-AZ RDS configuration, Amazon RDS automatically provisions and maintains a synchronous standby replica in a different Availability Zone. The data on the standby replica is consistent with the primary database, helping to ensure rapid failover in case of a problem.
What is the purpose of versioning in Amazon S3?
Versioning allows you to preserve, retrieve, and restore every version of every object in your Amazon S3 bucket. This makes it easier to recover from both unintended user actions and application failures.
What AWS service would be best for restoring an entire EC2 instance?
AWS Backup service is the best way to restore an entire EC2 instance. It centralizes and automates the backup of data across AWS services.
How can you accelerate the transfer of large amounts of data into AWS?
With AWS Snowball, a petabyte-scale data transport solution, and AWS Direct Connect, which provides a dedicated network connection, the data transfer can be accelerated.
How can Amazon S3 provide disaster recovery solution?
By using functionalities like Cross-Region Replication (CRR), versioning, multi-factor authentication deletion, and lifecycle policies, Amazon S3 can provide a robust disaster recovery solution.
Which AWS tool allows you to automate disaster recovery (DR)?
AWS Cloudformation allows you to document and version control your infrastructure, which can then be used to automate disaster recovery.
How can you access snapshots for disaster recovery in AWS?
Snapshots of EBS volumes, RDS databases, and Redshift clusters can be accessed from the AWS Management Console, AWS CLI, or through AWS SDKs, and restored to launch a new set of resources for disaster recovery.
Can we perform an in-place restore with AWS Backup?
Yes, AWS Backup allows us to perform both in-place restores (restoring the backup over the original resource) and out-of-place restores (restoring the backup to a new resource).
How can the AWS Storage Gateway help in data recovery?
AWS Storage Gateway service enables hybrid cloud storage between on-premises environments and the AWS Cloud. It integrates with AWS backup services offering a common method of data protection.
Can we restore an individual file from an EBS snapshot?
Typically, EBS snapshots capture the entire EBS volume. However, depending on the file system used, you may be able to mount the snapshot to an Amazon EC2 instance and recover individual files.
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