Resizing an instance backed by an EBS drive on ec2

ec2-ebs-instance-resize.sh

# IMPORTANT: On your machine, with the ec2 instance running
# Basic Config variables
instanceid=<instance-id>
size=50

#Get the root EBS volume id and availability zone for this instance:
oldvolumeid=$(ec2-describe-instances $instanceid |
  egrep "^BLOCKDEVICE./dev/sda1" | cut -f3)
zone=$(ec2-describe-instances $instanceid | egrep ^INSTANCE | cut -f12)
echo "instance $instanceid in $zone with original volume $oldvolumeid"

#Stop (not terminate!) the instance:
ec2-stop-instances $instanceid

#Detach the original volume from the instance:
while ! ec2-detach-volume $oldvolumeid; do sleep 1; done

#Create a snapshot of the original volume:
snapshotid=$(ec2-create-snapshot $oldvolumeid | cut -f2)
while ec2-describe-snapshots $snapshotid | grep -q pending; do sleep 1; done
echo "snapshot: $snapshotid"

#Create a new volume from the snapshot, specifying a larger size:
newvolumeid=$(ec2-create-volume   --availability-zone $zone       --size $size                    --snapshot $snapshotid |
  cut -f2)
echo "new volume: $newvolumeid"

#Attach the new volume to the instance:
ec2-attach-volume          --instance $instanceid   --device /dev/sda1       $newvolumeid
while ! ec2-describe-volumes $newvolumeid | grep -q attached; do sleep 1; done

#Start the instance and find its new public IP address/hostname. (If you were using an elastic IP address, re-assign it to the instance.)
ec2-start-instances $instanceid
while ! ec2-describe-instances $instanceid | grep -q running; do sleep 1; done
ec2-describe-instances $instanceid


# IMPORTANT: Connect to the instance with ssh (not shown) and resize the root file system to fill the new EBS volume:
# ext3 root file system (most common)
sudo resize2fs /dev/xvda1

#Show that the root file system is the new, larger size (20 GB):
df -h /

# IMPORTANT: Back on your machine
#Delete the old EBS volume and snapshot if you no longer need them, though I recommend you at least keep the snapshot for a while just in case:
ec2-delete-volume $oldvolumeid
ec2-delete-snapshot $snapshotid

Thanks, I found it useful.