Right-sizing resources in AWS - Commands & Configuration

Introduction

Right-sizing resources means choosing the best size and type of cloud resources like servers or databases to match your needs. This helps avoid paying too much for unused power or having too little power to run your apps smoothly.

When your cloud server is often idle but you still pay for it.

When your app slows down because the server is too small.

When you want to save money by using only what you need.

When you want to improve app performance by upgrading resources.

When you want to plan for future growth without waste.

Commands

This command fetches the average CPU usage of an EC2 instance over one day to see how much processing power it uses.

Terminal

aws cloudwatch get-metric-statistics --namespace AWS/EC2 --metric-name CPUUtilization --dimensions Name=InstanceId,Value=i-0123456789abcdef0 --start-time 2024-06-01T00:00:00Z --end-time 2024-06-02T00:00:00Z --period 3600 --statistics Average

Expected Output

{

    "Label": "CPUUtilization",

    "Datapoints": [

        {"Timestamp": "2024-06-01T01:00:00Z", "Average": 12.5},

        {"Timestamp": "2024-06-01T02:00:00Z", "Average": 15.3},

        {"Timestamp": "2024-06-01T03:00:00Z", "Average": 10.1}

    ]

}

→

--namespace - Specifies the AWS service to get metrics from

→

--metric-name - Specifies the metric to retrieve

→

--dimensions - Filters metrics by resource ID

→

--start-time - Start of the time range for metrics

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--end-time - End of the time range for metrics

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--period - Granularity of data points in seconds

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--statistics - Type of statistic to retrieve

This command changes the EC2 instance type to a medium size, adjusting resources to better fit the workload based on usage data.

Terminal

aws ec2 modify-instance-attribute --instance-id i-0123456789abcdef0 --instance-type t3.medium

Expected Output

No output (command runs silently)

→

--instance-id - Specifies which instance to modify

→

--instance-type - Sets the new instance size

This command checks the current configuration of the EC2 instance to confirm the new size is applied.

Terminal

aws ec2 describe-instances --instance-ids i-0123456789abcdef0

Expected Output

{

    "Reservations": [

        {

            "Instances": [

                {

                    "InstanceId": "i-0123456789abcdef0",

                    "InstanceType": "t3.medium",

                    "State": {"Name": "running"}

                }

            ]

        }

    ]

}

→

--instance-ids - Specifies which instance to describe

Key Concept

If you remember nothing else from this pattern, remember: monitor your resource usage first, then adjust size to match actual needs to save money and improve performance.

Common Mistakes

Changing instance size without checking current usage metrics.

You might pick a size too big or too small, wasting money or hurting performance.

Always check usage data like CPU or memory before resizing.

Not stopping the instance before changing certain instance types.

Some instance types require the instance to be stopped before resizing, or the command will fail.

Stop the instance first using 'aws ec2 stop-instances' before modifying the instance type if needed.

Summary

Use CloudWatch metrics to monitor resource usage like CPU before resizing.

Modify the instance type to better fit your workload based on usage data.

Verify the change by describing the instance to confirm the new size.

Practice

1. What does right-sizing mean in cloud resource management?

easy

A. Always picking the largest resource available

B. Choosing the best resource size to match your actual needs

C. Using resources without monitoring their usage

D. Ignoring cost and focusing only on performance

Solution

1. Step 1: Understand the meaning of right-sizing

   Right-sizing means selecting resources that fit your workload requirements without waste.

2. Step 2: Compare options to definition

   Only Choosing the best resource size to match your actual needs matches the idea of matching resource size to actual needs.

3. Final Answer:

   Choosing the best resource size to match your actual needs -> Option B

4. Quick Check:

   Right-sizing = best fit resource size [OK]

Hint: Right-sizing means matching size to need, not max or ignore usage [OK]

Common Mistakes:

• Thinking right-sizing means always picking the biggest resource
• Ignoring usage data when choosing resources
• Confusing right-sizing with ignoring costs

2. Which AWS service helps you analyze resource usage to right-size your EC2 instances?

easy

A. AWS CloudTrail

B. AWS Cost Explorer

C. AWS Trusted Advisor

D. AWS Lambda

Solution

1. Step 1: Identify AWS services for resource optimization

   AWS Trusted Advisor provides recommendations including right-sizing EC2 instances.

2. Step 2: Eliminate unrelated services

   CloudTrail logs API calls, Cost Explorer shows costs, Lambda runs code; only Trusted Advisor analyzes usage for right-sizing.

3. Final Answer:

   AWS Trusted Advisor -> Option C

4. Quick Check:

   Trusted Advisor = right-sizing help [OK]

Hint: Trusted Advisor gives right-sizing tips for EC2 [OK]

Common Mistakes:

• Confusing CloudTrail with usage analysis
• Thinking Cost Explorer directly suggests right-sizing
• Selecting Lambda which is unrelated to resource sizing

3. You have an EC2 instance running at 10% CPU most of the time. What is the likely output of a right-sizing recommendation script?

medium

A. Recommend upgrading to a larger instance type

B. Recommend no change to instance size

C. Recommend terminating the instance

D. Recommend downgrading to a smaller instance type

Solution

1. Step 1: Analyze CPU usage data

   10% CPU usage means the instance is underutilized and likely oversized.

2. Step 2: Determine right-sizing action

   Underutilization suggests downgrading to a smaller instance to save cost.

3. Final Answer:

   Recommend downgrading to a smaller instance type -> Option D

4. Quick Check:

   Low CPU usage = downsize instance [OK]

Hint: Low CPU means smaller instance recommended [OK]

Common Mistakes:

• Choosing to upgrade when usage is low
• Thinking no change is needed despite low usage
• Confusing termination with right-sizing

4. A user tries to right-size an EC2 instance but gets an error: "Instance type not supported in this AZ." What is the best fix?

medium

A. Change the instance type to one supported in the availability zone

B. Ignore the error and try again

C. Terminate the instance immediately

D. Switch to a different AWS region without checking

Solution

1. Step 1: Understand the error context

   The error means the chosen instance type is not available in the current availability zone.

2. Step 2: Apply correct fix

   Selecting an instance type supported in the same availability zone resolves the error.

3. Final Answer:

   Change the instance type to one supported in the availability zone -> Option A

4. Quick Check:

   Unsupported instance type in AZ = pick supported type [OK]

Hint: Pick instance types supported in your AZ [OK]

Common Mistakes:

• Ignoring the error and retrying
• Terminating instance without fixing
• Switching regions without checking availability

5. You manage a fleet of EC2 instances with varying CPU usage. Which approach best applies right-sizing to reduce costs without hurting performance?

hard

A. Start with smallest instance types, monitor usage, then scale up as needed

B. Always pick the largest instance type to avoid performance issues

C. Randomly change instance types monthly without monitoring

D. Terminate all instances and switch to on-demand only

Solution

1. Step 1: Understand right-sizing best practice

   Right-sizing means starting small and adjusting based on real usage data to avoid waste.

2. Step 2: Evaluate options for cost and performance balance

   Start with smallest instance types, monitor usage, then scale up as needed follows best practice by starting small, monitoring, and scaling up only if needed.

3. Final Answer:

   Start with smallest instance types, monitor usage, then scale up as needed -> Option A

4. Quick Check:

   Start small + monitor + scale = right-sizing [OK]

Hint: Start small, watch usage, then adjust size [OK]

Common Mistakes:

• Always picking largest instance wastes money
• Changing types randomly causes instability
• Terminating all instances ignores workload needs