Question

I have a EBS backed EC2 instance. I take snapshot for the EBS volume a few times say s1, s2, s3 where s3 being the last one took. Now I need to launch another EBS backed EC2 instance and also want to apply the snapshot took earlier onto the EBS volume of the new instance. I know that the EBS snapshots were taken incrementally, meaning that only the changed blocks since last snapshot will be captured. I wonder if I only apply the last snapshot (s3) on to the new EBS volume, does it mean that the data captured in s1 and s2 won’t get on to the new volume? Or put in another way, do I need to apply s1, s2, s3 sequentially and manually on to the new volume in order to get the full data set?

Answer 1

When you launch a new image from an EBS snapshot from s3, you will get the full state the EBS instance was in when you created s3.

Snapshots are created using an incremental method to increase performance, but you will get back the state consistent with the entire system from a given snapshot.

Even though the snapshots are saved incrementally, when you delete a snapshot, only the data not needed for any other snapshot is removed. So regardless of which prior snapshots have been deleted, all active snapshots will contain all the information needed to restore the volume.

http://aws.amazon.com/ebs/