[one-users] "Hybrid Cloud" - OpenNebula/Eucalyptus/etc.

[Philipp A. Hechter]

Hello everyone,

I'm having a hard time in understanding some parts of cloud computing,
esp. what the exact definition of a "Hybrid Cloud" is. If you guys could
help me with the following questions, that would be great. Thanks.

* Both OpenNebula and Eucalyptus have so called cloud controllers. Why
  is there a dedicated machine to handle the cloud? Can it be on the
  same host as a node?

    * OpenNebula supports 'hybrid clouds'. What exactly is the
      definition of a hybrid cloud?

          o Is it only a common interface for completely different
            clouds?

          o Or is it possible in a hybrid cloud to move images between
            different clouds? For example, move a KVM/QEMU image to
            Amazon EC2 with OpenNebula?

          o If it is the former one (just a common interface), how is
            it possible to "scale out" if the images are incompatible?

    * Eucalyptus says it is EC2 compatible, but it seems to me it it
      only API-compatible, not image-compatible.
          o Can one move a Amazon image AMI to a eucalyptus cloud?

I hope some of the questions are not too off-topic, but I had no idea
who else to ask...

Regards,
Philipp