If you upgraded from a micro instance (or any instance that only has EBS storage), it won't be included by default. In any case, you can add it by creating a snapshot of your instance and relaunching. You can add it on the Snapshot page, or in the Launch wizard when launching from an existing AMI.
- Open EC2 Web Admin Console.
- Click on Instances on the left, select your instance, click the "Actions" dropdown, then select "Create Image".
- On the snapshot page enter a name and description. You can add the Instance Store here if you like or later when you launch the AMI. Click the Add Volume button. Select "Instance Store 0" as the type, and whatever device path you like. Then click "Create Image".
- Go to AMIs under the images section on the left site of the EC2 Admin Console.
- Wait for the AMI status of your new image to be "available".
- Select the new AMI, click Launch at the top and go through the launch wizard (go through the steps, so you can set it up with the same security group and key pair as your current server).
- On step 4 you have a chance to modify the volumes again. Make sure "Instance Store 0" is listed as the second volume.
- Finish wizard and wait for launch. When you login df -h will show the volume.
Some recommend stopping the instance before the snapshot, but I've never had a problem. In my experience (using an ELB in front) the server is usually unavailable for up to 10 minutes while the snap is made.
[ec2-user@ABCD ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/xvda1 7.9G 2.3G 5.6G 29% /
tmpfs 829M 0 829M 0% /dev/shm
/dev/xvdb 147G 188M 140G 1% /media/ephemeral0
More info here: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html#Using_AddingDefaultLocalInstanceStorageToAMI