AWS AMI VS EBS Snapshot

1
votes

I have some questions in AWS - MYAMI

I have created one ec2 instance with t2 micro has 1gb ram Intel server with root volume

Then I have created an Ami image from that ec2 instance

Now when trying to launch an instance from Ami it's allowing to change from t2 to t3.

Questions:

  1. My Ami already has os installed of t2 and 1gb ram and Intel server installed. Why is it asking for the family again like t3,m4, etc when launching an instance?

  2. If I upgrade to t3 it's like I am again installing a new version of os in the existing machine. so my data in the existing machine would be erased off.

  3. what is the difference between AMI and EBS snapshot? Looks both similar if above 1 and 2 conditions are correct

1
amazon-web-servicesamazon-ec2amazon-ebs
Have you see that: stackoverflow.com/questions/17619580/… - Marcin

1 Answers

3
votes

The Instance Type determines the resources made available to the virtual machine, such as RAM and CPU.

The AMI is simply a copy of the boot disk. It contains the Operating System and any software that you installed on the disk.

When launching an instance from the AMI, the contents of the AMI will be copied to the boot disk of the new instance. When the disk boots, the operating system will look at the RAM available on the computer and automatically use it. It's just like upgrading your computer at home -- you would turn it off, install some more RAM or extra disks, then turn it on again. The operating system would see the extra resources and start using them.

Bottom line: AMI = Disk, Instance Type = Resources

An Amazon Machine Image (AMI) is exactly the same as an Amazon EBS Snapshot, except that:

  • A new instance can be launched from an AMI
  • An AMI can contain multiple snapshots (eg C: drive and D: drive)

Think of a Snapshot as a backup of the disk, and an AMI as a way of provisioning a boot disk for a new instance.