Disaster recovery strategies (backup, pilot light, warm standby) in AWS - Commands & Configuration

Introduction

Disasters can cause your cloud services to stop working. Disaster recovery strategies help you prepare so you can restore your services quickly. Backup, pilot light, and warm standby are three ways to keep your data safe and services running.

When you want to save copies of your data regularly to restore after accidental deletion or corruption.

When you want a minimal version of your system running in another region to quickly scale up after a disaster.

When you want a smaller but fully functional version of your system running to take over quickly if the main system fails.

When you want to reduce downtime by having a ready-to-use backup system.

When you want to balance cost and recovery speed by choosing the right recovery method.

Commands

This command downloads a backup file from an S3 bucket to your local machine. It is used to restore data from a backup.

Terminal

aws s3 cp s3://my-backup-bucket/backup-file.tar.gz ./

Expected Output

download: s3://my-backup-bucket/backup-file.tar.gz to ./backup-file.tar.gz

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cp - Copy files between S3 and local or between S3 buckets

This command deploys a minimal version of your infrastructure (pilot light) using CloudFormation. It sets up essential resources in another region.

Terminal

aws cloudformation deploy --template-file pilot-light-template.yaml --stack-name pilot-light-stack --region us-east-1

Expected Output

Waiting for stack create/update to complete...

Successfully created/updated stack - pilot-light-stack

→

--template-file - Specifies the CloudFormation template file to use

→

--stack-name - Names the CloudFormation stack

→

--region - Specifies the AWS region to deploy the stack

This command increases the number of running instances in the warm standby environment to handle traffic after a disaster.

Terminal

aws autoscaling update-auto-scaling-group --auto-scaling-group-name warm-standby-asg --desired-capacity 2 --region us-east-1

Expected Output

No output (command runs silently)

→

--auto-scaling-group-name - Specifies the name of the Auto Scaling group to update

→

--desired-capacity - Sets the number of instances to run

→

--region - Specifies the AWS region

This command checks the status of instances in the warm standby environment to ensure they are running and ready.

Terminal

aws ec2 describe-instances --filters Name=tag:Environment,Values=warm-standby --region us-east-1

Expected Output

{

    "Reservations": [

        {

            "Instances": [

                {

                    "InstanceId": "i-0abcd1234efgh5678",

                    "State": {

                        "Name": "running"

                    },

                    "Tags": [

                        {

                            "Key": "Environment",

                            "Value": "warm-standby"

                        }

                    ]

                }

            ]

        }

    ]

}

→

--filters - Filters instances by tags or other criteria

→

--region - Specifies the AWS region

Key Concept

If you remember nothing else from this pattern, remember: disaster recovery strategies balance cost and recovery speed by using backups, minimal setups, or ready-to-run standby systems.

Common Mistakes

Not regularly updating or testing backups

Backups may be outdated or corrupted, making recovery impossible or incomplete.

Schedule regular backups and perform test restores to ensure data integrity.

Deploying pilot light or warm standby environments in the same region as the primary system

A regional disaster can affect both environments, defeating the purpose of disaster recovery.

Deploy recovery environments in different AWS regions to ensure availability.

Not scaling up warm standby instances after a disaster

The standby environment remains under-provisioned and cannot handle production traffic.

Use commands or automation to increase capacity in the warm standby environment promptly.

Summary

Use AWS S3 to store and retrieve backups for data recovery.

Deploy a pilot light environment with minimal resources using CloudFormation to prepare for quick scaling.

Manage warm standby environments with Auto Scaling groups to keep a ready-to-use system running.

Verify the status of standby instances to ensure they are operational before switching traffic.

Practice

1. Which disaster recovery strategy involves keeping a minimal version of your environment running to quickly scale up after a failure?

easy

A. Pilot light

B. Backup

C. Warm standby

D. Cold standby

Solution

1. Step 1: Understand pilot light strategy

   Pilot light keeps a minimal core of your environment running, like a small copy of critical systems.

2. Step 2: Compare with other strategies

   Backup stores data but requires full rebuild; warm standby runs a scaled-down version ready to take over; cold standby is offline.

3. Final Answer:

   Pilot light -> Option A

4. Quick Check:

   Minimal running core = Pilot light [OK]

Hint: Minimal running core means pilot light strategy [OK]

Common Mistakes:

• Confusing warm standby with pilot light
• Thinking backup keeps systems running
• Assuming cold standby is always active

2. Which AWS service is commonly used to create backups for disaster recovery?

easy

A. Amazon S3

B. Amazon EC2

C. AWS Lambda

D. Amazon VPC

Solution

1. Step 1: Identify backup storage service

   Amazon S3 is designed for durable, scalable storage, ideal for backups.

2. Step 2: Exclude other services

   EC2 is compute, Lambda is serverless code, VPC is networking, none are primarily for backups.

3. Final Answer:

   Amazon S3 -> Option A

4. Quick Check:

   Backup storage = Amazon S3 [OK]

Hint: Backup storage in AWS is Amazon S3 [OK]

Common Mistakes:

• Choosing EC2 as backup storage
• Confusing Lambda with storage
• Selecting VPC for backups

3. Given a warm standby setup in AWS, which of the following best describes its state before a disaster occurs?

medium

A. Fully scaled production environment running in parallel

B. Minimal core systems running, rest offline

C. No environment running, only backups stored

D. Scaled-down but fully functional environment running

Solution

1. Step 1: Understand warm standby state

   Warm standby runs a scaled-down but fully functional environment ready to take over quickly.

2. Step 2: Compare with other options

   Fully scaled parallel is active-active, minimal core is pilot light, no environment is backup only.

3. Final Answer:

   Scaled-down but fully functional environment running -> Option D

4. Quick Check:

   Warm standby = scaled-down functional environment [OK]

Hint: Warm standby runs scaled-down functional environment [OK]

Common Mistakes:

• Confusing warm standby with full production
• Mixing pilot light with warm standby
• Thinking backup means no running environment

4. You set up a pilot light disaster recovery strategy but notice recovery time is longer than expected. What is the most likely cause?

medium

A. Backups are stored in Amazon S3

B. The pilot light environment is not fully configured and requires manual scaling

C. Warm standby environment is running at full capacity

D. The primary environment is still active

Solution

1. Step 1: Analyze pilot light recovery process

   Pilot light requires scaling up minimal systems to full production, so incomplete setup delays recovery.

2. Step 2: Exclude unrelated options

   Backups in S3 are normal; warm standby running full is unrelated; primary active is normal operation.

3. Final Answer:

   The pilot light environment is not fully configured and requires manual scaling -> Option B

4. Quick Check:

   Pilot light slow recovery = incomplete setup [OK]

Hint: Incomplete pilot light setup causes slow recovery [OK]

Common Mistakes:

• Blaming backups for slow recovery
• Confusing warm standby with pilot light
• Assuming primary environment affects recovery time

5. A company wants a disaster recovery solution that balances cost and recovery speed. They want a system running at all times but at reduced capacity, ready to scale up quickly. Which strategy should they choose?

hard

A. Backup only

B. Pilot light

C. Warm standby

D. Cold standby

Solution

1. Step 1: Understand company needs

   They want a running system at reduced capacity that can scale quickly, balancing cost and speed.

2. Step 2: Match needs to strategies

   Backup only is slow recovery; pilot light is minimal core only; cold standby is offline; warm standby runs scaled-down environment ready to scale.

3. Final Answer:

   Warm standby -> Option C

4. Quick Check:

   Running reduced capacity system = Warm standby [OK]

Hint: Running reduced capacity system means warm standby [OK]

Common Mistakes:

• Choosing pilot light for running full system
• Confusing backup with standby strategies
• Selecting cold standby for fast recovery