Detaching EBS volume

[yihua-yang]

Here are the points from AWS web site about detaching EBS volume:

– You can detach an Amazon EBS volume from an instance explicitly or by terminating the instance. However, if the instance is running, you must first unmount the volume from the instance.

– If an EBS volume is the root device of an instance, you must stop the instance before you can detach the volume.

A question from the test that ask:

What steps would you take to detach the root volume from the compromised EC2 instance?

The correct answer is
Stop the instance then detach the volume.

But from the AWS document it does not show the unmount and detach are mutual exclusive, on the contrary that one need to unmount first if the instance is still running, so should this one be the correct answer instead?

Unmount the volume, stop the instance, and then detach.

[Carlo-TutorialsDojo]

Hello yihua,

The “unmount” process is done at the OS level while the detach process is an AWS operation. If the EBS is just an additional volume, then you must unmount it first and detach. You can’t unmount a root volume. In the question, the instance is said to be an EBS-backed instance which implies that it is using an EBS volume as its root volume.

If an EBS volume is the root device of an instance, you must stop the instance before you can detach the volume.

Let me know if this answers your query.

Regards,

Carlo @ Tutorials Dojo

[yihua-yang]

Thanks for the reply. The AWS document need to be more clear about the distinction.