AMI EC2 EBS Backup- cost forecasting

Question

Actually I have to take forecast of costing for one my instance, which is having a number of volumes attached... These volumes are different in size and types.

Let's suppose I took the AMI backup and terminated the server.

Now my confusion is how would I calculate the cost. The cost will be calculated based on pricing of Amazon EBS Volumes or Amazon EBS Snapshot. Because the cost difference is just double.

Let me know if you can help me understanding.

pricing of Amazon EBS Volumes or Amazon EBS Snapshot Which I took from AWS Pricing : https://aws.amazon.com/ebs/pricing/

Answer 1

Amazon EBS snapshots are a complex subject due to the way they work.

There is a detailed explanation in: Amazon EBS snapshots - Amazon Elastic Compute Cloud

A quick summary is:

• Snapshots contain only the data that is different to previous snapshots (they are incremental)
• An AMI is actually a snapshot. So, if you booted a new Amazon EC2 instance from an AMI and then created a snapshot, the snapshot would contain very little since most of the volume was already contained in the previous snapshot (that was part of the AMI). Confused yet?
• Any snapshot can be deleted and information will still be retained to allow any other snapshot to be restored. So, the snapshot is actually an 'index' to the snapshot data, and the snapshot data is stored separately to the snapshot itself. You should be questioning your sanity at this point!

So, the cost of Amazon EBS snapshots is mostly based on how much the contents of the volume changes, and how many snapshots (effectively, points-in-time) you wish to keep. If you only keep the most recent snapshot, then all data will be available, but the cost will be minimised because it won't keep any data that has been deleted from the volume.

Bottom line: Snapshots take less space than the data on a volume due to the incremental natures. The more snapshots ("points-in-time"), the more data will be kept and hence the more cost.