Instance Store

The term “EBS backed” and “Instance Store Backed” may be confusing. When you launch an instance  you see this familiar screen. Note that for every single AMI the Root Device Type is “EBS backed”.

In other words for all these the root device will be EBS. If you choose community AMIs you can find some which are Instance Store backed.

I chose a Windows 2012 R2 Base AMI and click Next.

The Instance Storage column is marked “EBS Only” for many of the types, but here I have chosen an i3.large (about $0.15 an hour) which comes with 1*475 (SSD).  Click Next.

This shows me that the root volume is EBS, but it allows me to add more volumes. The additional volumes can be EBS or Instance Store. If I choose Instance Store I can only add exactly 1 instance store volume, which matches the 1*475 (SSD) on the previous screen. I can’t choose the size.

It also allows me to add multiple EBS volumes if I choose EBS in the drop down.

Once launched, you see the D: drive.  There is a text file named “Important” in the root of the drive.

Instance store can also be used for any instances which do not need retain their volumes after the instance is terminated, for example after a scale in activity.