The last slide informs us that to take a consistent snapshot we have to stop the instance and detach volume. Detach volume is required in this case? Stopping instance is obvious for me.
Great catch! It’s not actually required that you stop the instances to take a snapshot. You really have two options, you can freeze the file system to ensure that you get an accurate copy of the data, or you can simply detach the volume, create a snapshot, and once the status is in "pending" reattach the volume.
For more information please see the following link: