Root Device and Block Devices difference

Question

Can someone help me to understand the difference between Root device and Block devices for EC2 instance. You can see a snapshot i posted below.

What i tried to achieve is :

1. I created a snapshot of the attached volume of the EC2.

2. Detached the volume from instance.

3. Deleted the volume.
4. Created a new volume from the snapshot.
5. Reattached the newly created volume to the instance.

But it only attaches to the Block Devices but not to the root devices. And results in the failure to launch the instance.

My apologies if my question is wrong. Awaiting your reply.

Thanks in advance.

Inconsistent

FYI, a root device can be from a block storage type like EBS (which is the default option in AWS). – Manifesto

Answer 1

The Root device is the EBS volume for the AMI in which your instance is based on. This will contain the operating system. If not configured then, AWS will use the default values of the AMI.

You can configure additional Block device entries optionally to mount additional volumes on the instance, besides the root volume. It can be empty or from a snapshot.

Arsenite