EBS root instances seem to not have any instance storage

Question

EBS root instances seem to not have any instance storage - is this correct or some odd bug?

I'm expecting to have /dev/sda to be the EBS backed volume, and then have the other instance storage devices there as /dev/sdb etc...

Is this an incorrect assumption?

Answer 1

It's not a bug. Unlike Ephemeral, EBS based instances don't give you any free storage.

You can however create a new EBS volume and attach it to your instance.

Cheers

Ray

EDIT: I believe I led you astray as this seems to have changed. You still cannot attach local disk to an existing running instance but this does seem to be possible at launch time. See: http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/index.html?Using_AddingDefaultLocalInstanceStorageToAMI.html

Taken from the above url, device mapping with an 80gb EBS root volume plus ephemeral storage.

https://ec2.amazonaws.com/
?Action=RegisterImage
&Name=MyImage
&KernelId=aki-f70657b2
&RamdiskId=ari-ff0d5cba
&RootDeviceName=/dev/sda1
&BlockDeviceMapping.1.DeviceName=/dev/sda1
&BlockDeviceMapping.1.Ebs.SnapshotId=snap-12345678
&BlockDeviceMapping.1.Ebs.VolumeSize=80
&BlockDeviceMapping.1.Ebs.DeleteOnTermination=false
&BlockDeviceMapping.2.DeviceName=/dev/sdc
&BlockDeviceMapping.2.VirtualName=ephemeral0
&...auth parameters...