I wanted to restore a windows ec2 instance's root volume from a snapshot in the past. But there was recently a patch done on that instance. So I wonder if the updates will be gone, i.e. if the entire os is stored on ebs as well and the instance will be reverted to the time before the windows patch.
Looks like it would store all the applications installed and files on there. I tried googling around, but can't understand the boundary of what's stored. Thanks in advance for the help!
An Amazon EBS Snapshot is a copy of the entire disk volume.
When a Snapshot is restored to a new EBS Volume, the disk will contain exactly the same data as the original disk at the time of the Snapshot.
The Amazon EBS service doesn't have any knowledge of the operating system being used. It's just acting as a block storage device.