AWS – Increasing the size of an EC2 instance’s primary EBS volume

This is really good guide:

http://cloud.tekgoblin.com/2013/04/29/aws-guides-how-to-increase-your-ec2-linux-root-volume-size/

basically stop your instance, detach the primary volume (/dev/sda1), create a snapshot from this ebs volume, create a volume (with increased diskspace) from the snapshot, attach the new bigger volume to the ec2 instance, as /dev/sda1.

start the instance again.