How to Increase and Decrease the Size of an Amazon EBS Volume

Amazon Elastic Block Store (EBS) allows you to increase the size of a volume dynamically without downtime. However, decreasing the size of an EBS volume is not supported directly, and you must follow a workaround.

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1. Increasing the Size of an EBS Volume

Amazon EBS supports volume resizing while keeping data intact.
Resizing involves three steps:
Modify the EBS volume size
Extend the partition
Resize the file system

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Steps to Increase EBS Volume Size (AWS Console)

Step 1: Modify the Volume

Open the AWS Management Console
Go to EC2 Dashboard → Elastic Block Store → Volumes
Select the EBS Volume you want to resize
Click Modify Volume
Increase the size (e.g., from 20GB to 50GB)
Click Modify → Confirm

AWS will resize the volume, and its state will change to optimizing.

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Step 2: Extend the Partition (Linux)

Connect to the EC2 instance via SSH:

ssh -i your-key.pem ec2-user@your-ec2-instance-ip

Check the available disk space:

lsblk

Example Output:

NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   50G  0 disk
└─xvda1 202:1    0   20G  0 part /

Resize the partition:

sudo growpart /dev/xvda 1

Resize the file system:
For ext4/xfs file systems, run:

sudo resize2fs /dev/xvda1  # For ext4  
sudo xfs_growfs /          # For XFS  

Verify the new size:

df -h

Now, your EBS volume has been successfully expanded!

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Step 2: Extend the Partition (Windows)

Open Disk Management
Right-click on the EBS volume
Click Extend Volume
Follow the wizard and expand the disk
Your EBS volume is now resized in Windows!

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2. Decreasing the Size of an EBS Volume (Workaround)

Amazon EBS does not allow shrinking a volume directly.
Workaround: Create a new smaller volume and migrate data.

Steps to Reduce EBS Volume Size

Create a snapshot of the original EBS volume.
Create a new smaller EBS volume from the snapshot.
Attach the new volume to the EC2 instance.
Copy the data from the old volume to the new one.
Detach and delete the old volume.

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Example (Using AWS CLI)

Create a snapshot of the existing volume:

aws ec2 create-snapshot --volume-id vol-0a1b2c3d4e5f6g7h8 --description "Backup before resizing"

Output:

{
    "SnapshotId": "snap-1234567890abcdef0"
}

Create a smaller volume from the snapshot:

aws ec2 create-volume --snapshot-id snap-1234567890abcdef0 --size 30 --availability-zone us-east-1a

Attach the new volume to the instance:

aws ec2 attach-volume --volume-id vol-0987654321abcdef0 --instance-id i-0123456789abcdef0 --device /dev/xvdf

Copy the data:

sudo rsync -avxHAX /mnt/old-volume/ /mnt/new-volume/

Detach and delete the old volume:

aws ec2 detach-volume --volume-id vol-0a1b2c3d4e5f6g7h8
aws ec2 delete-volume --volume-id vol-0a1b2c3d4e5f6g7h8

Now, you have a smaller EBS volume with your data intact.

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3. Summary

Operation	Supported by AWS?	Steps Required
Increase EBS Volume Size	Yes	Modify Volume → Extend Partition → Resize File System
Decrease EBS Volume Size	No	Create New Volume → Migrate Data → Delete Old Volume

Would you like an automated script to handle EBS resizing?