Comment 8 for bug 811226

Excerpts from Juan L. Negron's message of Fri Sep 02 00:09:16 UTC 2011:
> Are you guys sure about the ebs backed instances?
>
> I explain ....
>
> Currently for oneiric, I am using ami-f1448498 which is an instance store
> ami so, am I missing something here or is ensemble by "default" using
> ebs-root instances and I just changed them to instance store ones ?
>
> If indeed I am using instance-store images that are not being backed
> anywhere, it would be helpful to document this somewhere so not to confuse
> users.
>

Agreed Juan, its just "by default" using EBS backed AMI's. If you switch,
you have no safety net.

Also it turns out its not that much of a safety net anyway. The "big
meltdown" on EC2 a few months ago happened because people were using
snapshots as backups. But snapshots live in the same availability zone
as your instance, so you may not be able to reach the snapshot when your
instance has died (as many people found out when they tried to enact
their disaster recovery plan of pulling their snapshots onto other hosts).

Its ok though, we can simply make it clear that Ensemble doesn't take
care of this for you, and you need to manage your own data storage and
backups. Having co-located formulas so people can roll out a backup
service to all their nodes would be a nice start at this.