Upgrading an Amazon EC2 instance from t1.micro to medium, instance storage remains same
Keep in mind, EBS storage (which you are currently using) and Instance storage (which is what you are looking for) are two different things in EC2.
EBS storage is similar to a SAN volume. It exists outside of the host. You can create multiple EBS volumes of up to 1TB and attach them to any instance size. Smaller instances have lower available bandwidth to EBS volumes so they will not be able to effectively take advantage of all that many volumes.
Instance storage is essentially hard drives attached to the host. While its included in the instance cost, it comes with some caveats. It is not persistent. If you stop your instance, or the host fails for any reason, the data stored on the instance store will be lost. For this reason, it has to be explicitly enabled when the instance is first launched.
Generally, its not recommended that to use instance storage unless you are conformable with and have designed your infrastructure around the non-persistance of instance storage.
The sizes mentioned for the instance types are just these defaults. If you create an image from a running micro instance, it will get that storage size as default, even if this image later is started as medium.
But you can change the storage size when launching the instance:
You also can change the default storage size when creating an image:
WARNING: This will resize the storage size. It will not necessarily resize the partition existing on it nor will it necessarily resize the file system on that partition. On Linux it resized everything automagically (IIRC), on a Windows instance you will have to resize your stuff yourself. For other OSes I have no idea.
I had a similar situation. I created a m2.medium instance of 400 GB, but when I log into the shell and issue the command
df -h
... it shows an 8 GB partition.
However, the command
sudo fdisk -l
showed that the device was indeed 400 GB. The problem is that Amazon created a default 8 GB partition on it, and that partition needs to be expanded to the full size of the device. The command to do this is:
sudo resize2fs -f /dev/xvda1
where /dev/xvda1 is the mounted root volume. Use the 'df -h' command to be sure you have the right volume name.
Then simply reboot the instance, log in again, and you'll see the fdisk command now says there's nearly 400 GB available space. Problem solved.