Store and Register your EC2 machine image

To retrieve your machine image later, your machine image should be stored in S3. To do that, there are multiple steps required.

Step 1) Copy your X.509 certificate and private key to your instance.
scp -i id_rsa-gsg-keypair pk-HKZYKTAIG2ECMXYIBH3HXV4ZBZQ55CLO.pem cert-HKZYKTAIG2ECMXYIBH3HXV4ZBZQ55CLO.pem root@domU-12-34-31-00-00-05.compute-1.amazonaws.com:/mnt

This is done on your local desktop. Than, your security files will be stored in /mnt directory of your instance.

Step 2) Now you have to bundle your instance with the commmand:
ec2-bundle-vol -d /mnt -k /mnt/pk-HKZYKTAIG2ECMXYIBH3HXV4ZBZQ55CLO.pem -c /mnt/cert-HKZYKTAIG2ECMXYIBH3HXV4ZBZQ55CLO.pem -u 495219933132 -r i386 -p sampleimage

This takes some time. (several minutes) If it was successful, you can see the bundled files under your /mnt directory. They are bunch of files with names of smapleimage*.

Step 3) Upload bundled files to S3 from your instance
ec2-upload-bundle -b -m /mnt/sampleimage.manifest.xml -a -s

I had some problem with this process. Although I have S3 access, this command complained that I don't have S3 access. Interestingly, I created a bucket in S3 manually, and it worked.
I use the firefox extension that recommanded in a EC2 forum.
http://www.s3fox.net/
It is quite useful. If I want to sync part of my disk, it would be a great tool.

Step 4) Then, logout your instance, and on your desktop,
ec2-register /sampleimage.manifest.xml

Now you can see your machine image from,
ec2-describe-images -o self

Step 5) That's it! whenever you want to reload your machine image,
ec2-run-instances ami-5bae4b32

for the longer version of tutorial,
http://docs.amazonwebservices.com/AWSEC2/latest/GettingStartedGuide/