How to resize EC2 instance

AwsHow-ToBeginner · 3 min read

How to Resize an EC2 Instance on AWS Easily

To resize an EC2 instance, first stop the instance, then change its InstanceType to the desired size in the AWS Management Console or CLI, and finally start the instance again. This process updates the instance's hardware resources like CPU and memory without losing data on the attached volumes.

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Syntax

To resize an EC2 instance using AWS CLI, use the modify-instance-attribute command with the --instance-type option. The instance must be stopped before resizing.

--instance-id: The ID of the EC2 instance to resize.
--instance-type: The new instance type (e.g., t3.medium).

bash

aws ec2 stop-instances --instance-ids i-1234567890abcdef0
aws ec2 modify-instance-attribute --instance-id i-1234567890abcdef0 --instance-type "{\"Value\":\"t3.medium\"}"
aws ec2 start-instances --instance-ids i-1234567890abcdef0

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Example

This example shows how to resize an EC2 instance from t2.micro to t3.medium using AWS CLI. The instance is stopped first, resized, then started again.

bash

aws ec2 stop-instances --instance-ids i-0abcdef1234567890
aws ec2 wait instance-stopped --instance-ids i-0abcdef1234567890
aws ec2 modify-instance-attribute --instance-id i-0abcdef1234567890 --instance-type "{\"Value\":\"t3.medium\"}"
aws ec2 start-instances --instance-ids i-0abcdef1234567890

Output

Stopped instance: i-0abcdef1234567890 Instance stopped. Modified instance type to t3.medium. Started instance: i-0abcdef1234567890

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Common Pitfalls

Trying to change the instance type while the instance is running will fail; always stop the instance first.
Not all instance types are available in every AWS region or compatible with your instance's AMI or EBS volume.
Failing to check instance limits or account quotas can block resizing.
Remember to verify your application compatibility with the new instance type.

bash

aws ec2 modify-instance-attribute --instance-id i-0abcdef1234567890 --instance-type "{\"Value\":\"t3.medium\"}"
# This will fail if the instance is running.

# Correct approach:
aws ec2 stop-instances --instance-ids i-0abcdef1234567890
aws ec2 wait instance-stopped --instance-ids i-0abcdef1234567890
aws ec2 modify-instance-attribute --instance-id i-0abcdef1234567890 --instance-type "{\"Value\":\"t3.medium\"}"
aws ec2 start-instances --instance-ids i-0abcdef1234567890

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Quick Reference

Remember these steps to resize your EC2 instance:

Stop the instance.
Modify the instance type.
Start the instance again.
Check compatibility and limits before resizing.

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Key Takeaways

Always stop your EC2 instance before changing its instance type.

Use the AWS CLI or Console to modify the instance type safely.

Verify the new instance type is available and compatible with your setup.

Restart the instance after resizing to apply changes.

Check AWS limits and application compatibility before resizing.