Will I lose my data when I shut down instances?

We don't add EBS volumes to every instance by default, only where it makes sense. EBS volumes aren't exactly cheap so we're trying not to be wasteful with resources. Obviously your database master is among the instances that needs persistence, so it gets a volume that's 10 GB in size by default.

You can configure more volumnes on a per-role basis like outlined in the screenshot below, we will initialize them for you, by default using XFS, after that you're free to do whatever with them, referencing them either in your cookbooks, or use them from within your application.

EBS volumes will stay active until you decide to remove them. When you delete an instance we'll ask you if you want to remove the volumes that were attached to it as well.