[one-users] Persistent VM image

Steven Timm timm at fnal.gov
Tue Sep 6 06:49:52 PDT 2011

On Tue, 6 Sep 2011, GiBu GeorGe wrote:

> Hai...
> My primary language is not english so i am having difficluty in
> understanding Persistent image concept..
> What i am trying to do is port my existing servers to opennebula.. But i
> want those vm to act as virtual machine normally would... Means if any
> changes made to it wont disappear if the server restart(physical/logical)..
> Does making it persisatant help with that option... Or i am getting it all
> wrong here..

It depends on how you set up your image repository.
My setup is:

a) image repository on the head node
b) images copied to vm host via tm_ssh

In that case a "persistent" VM means that your VM is copied from
the repository when you do "onevm create" and saved back to the
repository when you do "onevm shutdown".
As other people have pointed out, the state of the VM is stored
in a file on the VM host so you do not lose files on a reboot
(either inside the VM or of the VM host).

If you want more persistent than that, you should consider
a shared file system such as a SAN.  that way you are running
off of the master persistent copy all the time.

Steve Timm

Steven C. Timm, Ph.D  (630) 840-8525
timm at fnal.gov  http://home.fnal.gov/~timm/
Fermilab Computing Division, Scientific Computing Facilities,
Grid Facilities Department, FermiGrid Services Group, Group Leader.
Lead of FermiCloud project.

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