Amazon EBS volumes: How to Shrink ’em Down to Size

Have you ever launched an EC2 instance with Amazon EBS (Elastic Block Store) storage only to realize that your EBS storage is way over-allocated and you have no idea on how to reduce it?

Amazon’s Elastic Block Store Volumes are easy to use and expanding them is no problem at all, but for some reason, there’s no obvious way to reduce them. This is especially problematic when the EBS volume is mounted on the root.

It turns out that there’s nothing to worry about. I’ll take you through an easy way to reduce your volumes so you can hopefully save yourself some money.

Reducing AWS EBS Volumes

EC2 Instance with 20GB Amazon EBS Volume

For the purpose of this exercise, I created an instance and launched it with a 20GB Amazon EBS volume:

Assuming we want to reduce this to 8GB, the first thing we will need to do is to make a note of the root volume’s block device name and our instance’s availability zone
Instance availability zone
So in my case, the details are
Block Device Name = /dev/sda1
Availability Zone = ap-southeast-2b

Stop the Instance:

Instance state drop down (Start, Stop, Reboot, Terminate)

Create a snapshot of the root volume:

AWS EBS - Create a first snapshot of the root volume

Create a second Amazon EBS volume:

Using the snapshot, create a second volume – of the original size – in the same availability zone as your instance.
Amazon EBS - Create a second snapshot of the root volume
Hopefully, you will have something like this:
AWS EBS - Summary of Availability Zones

Create an empty 8GB Amazon EBS volume in the same availability zone

AWS EBS - Attaching both volumes to the instance
attach both volumes to the instance and again note all device name details.

Create 8GB Amazon EBS volume
Now, attach both volumes to the instance and again note all device name details.

Block Device Name Big Volume = /dev/sda1
Block Device Name Big Volume Snapshot = /dev/sdg
Block Device Name Small Volume = /dev/sdf

Restart the Instance and SSH in

Login:

ssh -i <Private-key> ec2-user@ip-address

Create a file system for the 2 volumes you have created (Note: In Ubuntu I had to do a cat/proc/partitions to work out which device was which).

sudo mkfs -t ext4 /dev/xvdf
sudo mkfs -t ext4 /dev/xvdg

Create two mount directories and mount the new volumes.

sudo mkdir /mnt/small
sudo mount /dev/xvdf /mnt/small
sudo mkdir /mnt/snap
sudo mount /dev/xvdg1 /mnt/snap

Sync the files.

sudo rsync -aHAXxSP /mnt/snap/ /mnt/small

Unmount the smaller volume.

sudo umount /dev/xvdf

Stop the instance

Detach all volumes.
AWS EBS - Detaching all volumes
Attach the small volume to the Block Device Name from the first step.
Block Device Name = /dev/sda1
AWS EBS - Attaching the small volume to the Block Device Name from the first step
Now you can restart your instance and verify that it is working correctly.

I recommend taking a look at Cloud Academy’s Managing Instance Volumes Using EBS Hands-on Lab if you want to learn to create an EC2 instance with an additional EBS volume.

IMPORTANT Don’t forget to delete your snapshot and the two other volumes that are no longer needed. That can save you some big bucks.

Avatar

Written by

Michael Sheehy

I have been UNIX/Linux System Administrator for the past 15 years and am slowly moving those skills into the AWS Cloud arena. I am passionate about AWS and Cloud Technologies and the exciting future that it promises to bring.


Related Posts

Amanda Cross
Amanda Cross
— April 9, 2021

New Content: Platforms, Programming, and DevOps – Something for Everyone

This month our team of expert certification specialists released three new or updated learning paths, 16 courses, 13 hands-on labs, and four lab challenges! New content on Cloud Academy You can always visit our Content Roadmap to see what’s just released as well as what’s coming soon....

Read more
  • alibaba
  • AWS
  • Azure
  • DevOps
  • Google Cloud Platform
  • programming
  • Security
Luca Casartelli
Luca Casartelli
— March 31, 2021

Mastering AWS Organizations Service Control Policies

Service Control Policies (SCPs) are IAM-like policies to manage permissions in AWS Organizations. SCPs restrict the actions allowed for accounts within the organization making each one of them compliant with your guidelines. SCPs are not meant to grant permissions; you should consider ...

Read more
  • AWS
  • Organizations
  • SCP
Amanda Cross
Amanda Cross
— March 12, 2021

New Content: Focus on DevOps and Programming Content this Month

This month our team of expert certification specialists released 12 new or updated learning paths, 15 courses, 25 hands-on labs, and four lab challenges! New content on Cloud Academy You can always visit our Content Roadmap to see what’s just released as well as what’s coming soon. Ja...

Read more
  • alibaba
  • AWS
  • Azure
  • DevOps
  • Google Cloud Platform
  • programming
Amanda Cross
Amanda Cross
— February 12, 2021

New Content: Get Ready for the CISM Cert Exam & Learn About Alibaba, Plus All the AWS, GCP, and Azure Courses You Know You Can Count On

This month our team of intrepid certification specialists released five learning paths, seven courses, 19 hands-on labs, and three lab challenges!  One particularly interesting new learning path is Certified Information Security Manager (CISM) Foundations. After completing this learn...

Read more
  • alibaba
  • AWS
  • Azure
  • cism
  • DevOps
  • Google Cloud Platform
  • programming
Avatar
Cloud Academy Team
— January 31, 2021

Which Certifications Should I Get?

The old AWS slogan, “Cloud is the new normal” is indeed a reality today. Really, cloud has been the new normal for a while now and getting credentials has become an increasingly effective way to quickly showcase your abilities to recruiters and companies. With all that in mind, the s...

Read more
  • AWS
  • Azure
  • Certifications
  • Cloud Computing
  • Google Cloud Platform
Avatar
Andrew Larkin
— January 31, 2021

The 12 AWS Certifications: Which is Right for You and Your Team?

As companies increasingly shift workloads to the public cloud, cloud computing has moved from a nice-to-have to a core competency in the enterprise. This shift requires a new set of skills to design, deploy, and manage applications in cloud computing. As the market leader and most ma...

Read more
  • AWS
  • AWS Certifications
Avatar
Stuart Scott
— January 29, 2021

AWS Certified Solutions Architect Associate: A Study Guide

Want to take a really impactful step in your technical career? Explore the AWS Solutions Architect Associate certificate. Its new version (SAA-C02) was released on March 23, 2020. The AWS Solutions Architect - Associate Certification (or Sol Arch Associate for short) offers some ...

Read more
  • AWS
  • AWS Certifications
  • AWS Certified Solutions Architect Associate
Amanda Cross
Amanda Cross
— January 7, 2021

New Content: AWS Terraform, Java Programming Lab Challenges, Azure DP-900 & DP-300 Certification Exam Prep, Plus Plenty More Amazon, Google, Microsoft, and Big Data Courses

This month our Content Team continues building the catalog of courses for everyone learning about AWS, GCP, and Microsoft Azure. In addition, this month’s updates include several Java programming lab challenges and a couple of courses on big data. In total, we released five new learning...

Read more
  • AWS
  • Azure
  • DevOps
  • Google Cloud Platform
  • Machine Learning
  • programming
Avatar
Stuart Scott
— December 17, 2020

Where Should You Be Focusing Your AWS Security Efforts?

Another day, another re:Invent session! This time I listened to Stephen Schmidt’s session, “AWS Security: Where we've been, where we're going.” Amongst covering the highlights of AWS security during 2020, a number of newly added AWS features/services were discussed, including: AWS Audit...

Read more
  • AWS
  • AWS re:Invent
  • cloud security
Joe Nemer
Joe Nemer
— December 4, 2020

AWS re:Invent: 2020 Keynote Top Highlights and More

We’ve gotten through the first five days of the special all-virtual 2020 edition of AWS re:Invent. It’s always a really exciting time for practitioners in the field to see what features and services AWS has cooked up for the year ahead.  This year’s conference is a marathon and not a...

Read more
  • AWS
  • AWS Glue Elastic Views
  • AWS re:Invent
Bryony Harrower
Bryony Harrower
— November 6, 2020

WARNING: Great Cloud Content Ahead

At Cloud Academy, content is at the heart of what we do. We work with the world’s leading cloud and operations teams to develop video courses and learning paths that accelerate teams and drive digital transformation. First and foremost, we listen to our customers’ needs and we stay ahea...

Read more
  • AWS
  • Azure
  • content roadmap
  • GCP
Joe Nemer
Joe Nemer
— October 25, 2020

Excelling in AWS, Azure, and Beyond – How Danut Prisacaru Prepares for the Future

Meet Danut Prisacaru. Danut has been a Software Architect for the past 10 years and has been involved in Software Engineering for 30 years. He’s passionate about software and learning, and jokes that coding is basically the only thing he can do well (!). We think his enthusiasm shines t...

Read more
  • AWS
  • careers
  • champions
  • upskilling