How To Convert from AWS Instance Family t2 to t3 with Enhanced Networking on Amazon Linux 1

Published Date Author: , Posted June 10th, 2021 at 1:19:03pm

I wanted to change instance type from t2 to t3, but got an error when i went to start the instance:

I found this AWS docs page: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking-ena.html

Below are the steps I need to follow on AWS Linux 1.

Summary Steps

Pre-flight tests on t2

modinfo ena
-> see “ERROR: modinfo: could not find module ena”
ethtool -i eth0 | grep ^driver:
-> see “driver: vif”

Install the latest drivers

sudo yum -y update
sudo reboot
modinfo ena | grep ^description:
-> see “description: Elastic Network Adapter (ENA)”

Convert the instance to t3 to get ENA working

aws ec2 stop-instances --instance-ids {instanceid}
aws ec2 modify-instance-attribute --instance-id {instanceid} --instance-type t3.large
aws ec2 start-instances --instance-ids {instanceid}
ethtool -i eth0 | grep ^driver:
-> see “driver: ena”

Detailed Steps

Ensure the latest drivers are installed:

sudo yum -y update

IMPORTANT: You must reboot once the updates are done!

After the reboot, check to ensure the driver is loaded properly:

modinfo ena

DRIVER NOT INSTALLED

DRIVER INSTALLED √

Enable ENA on the instance

aws ec2 modify-instance-attribute --instance-id {instanceid} --ena-support

Note: To disable ENA support, use this command:
aws ec2 modify-instance-attribute --instance-id {instanceid} --no-ena-support

Check that it is enabled

aws ec2 describe-instances --instance-ids {instanceid} --query "Reservations[].Instances[].EnaSupport"

You should see the string ‘True’ as the result when enabled, and nothing when disabled.

Stop the instance so you can change the instance type.

aws ec2 stop-instances --instance-ids {instanceid}

Change instance type from t2 to t3

aws ec2 modify-instance-attribute --instance-id {instanceid} --instance-type t3.large

Start the instance

aws ec2 start-instances --instance-ids {instanceid}

Check the interface

ethtool -i eth0

DRIVER NOT INSTALLED

DRIVER INSTALLED √

NOTE: As per the AWS docs -> “The following AMIs include the required ENA module and have ENA support enabled: Amazon Linux 2”

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