Hibernating Ubuntu on EBS boot EC2 instances

[Scott Moser]

On Wed, 3 Feb 2010, Eric Hammond wrote:

> Amazon EC2 has the ability to run "EBS boot AMIs" which keep a
> persistent root disk[1].  This lets a user shutdown (stop) and boot
> (start) a server without losing the contents of the root disk.
>
> There have been a number of people inquiring about the possibility of
> enhancing the Ubuntu on EC2 image so that during the stop/start cycle
> they can hibernate/resume as an alternative to shutdown/boot.
>
> I see there was some interest a while ago in getting hibernate to work
> with Eucalyptus[2].
>
> What steps would need to be taken to propose hibernate support be
> investigated for EC2, perhaps in the upcoming "M" cycle since it might
> be too late for Lucid?

To add something for consideration, the right process is to open a
blueprint.  Put some information there, and then we can look at it later.
I agree that this is probably not a lucid thing.

> Technical notes: Since hibernation cannot be done to the EC2 swap
> partition (not persistent) and (I think) hibernation cannot be done to a
> swap file on an active file system, this probably means that an
> additional EBS volume will need to be attached for swap (not difficult)
> or the main EBS volume will need to be split into multiple partitions
> for root and swap.

I've copied John on this, because he likely knows more about this than I
do.  However, I think that it may be technically difficult to do this
reliably on ec2.  The possibility of changing "hardware" on subsequent
boots seems like it might cause problem.  by changing hardware, I mean:
a.) different memory configurations due to --instance-type being changed
b.) uncontrollable changes in hardware on amazon.  I've occasionally seen
different memory amounts even within the same instance type.  I'm also not
sure if you're ever *guaranteed* to have identical cpu type, which may be
a requirement for hibernation.

Maybe John can help us out.  It definitely does sound like a nice feature,
but it would have some limitations.


> [1]http://aws.amazon.com/about-aws/whats-new/2009/12/03/amazon-ec2-instances-now-can-boot-from-amazon-ebs/
> [2]https://wiki.ubuntu.com/ServerKarmicCloudPowerManagement