[Openstack] Snapshotting ephemeral disks?

Lars Kellogg-Stedman lars at seas.harvard.edu
Thu Aug 16 13:58:15 UTC 2012


I have a system that I've booted using a live CD image (so
.../instance-<ID>/disk points at the ISO file).  I've installed an OS
onto /dev/vda (which is .../instance-<ID>/disk.local).

Running 'nova image-create <INSTANCE> <NAME>` results in a traceback in
the compute log:

  2012-08-16 09:48:56 TRACE nova.rpc.amqp ProcessExecutionError: Unexpected error while running command.
  2012-08-16 09:48:56 TRACE nova.rpc.amqp Command: qemu-img convert -f qcow2 -O iso -s 6966cceec946407eb12531ddbe7bb7ac /virt/pools/openstack_2/instance-0000004c/disk /tmp/tmpMJ9GuL/6966cceec946407eb12531ddbe7bb7ac
  2012-08-16 09:48:56 TRACE nova.rpc.amqp Exit code: 1
  2012-08-16 09:48:56 TRACE nova.rpc.amqp Stdout: ''
  2012-08-16 09:48:56 TRACE nova.rpc.amqp Stderr: "qemu-img: Unknown file format 'iso'\n"
  2012-08-16 09:48:56 TRACE nova.rpc.amqp 

And the image gets stuck in the "SAVING" state:

    # nova image-list
    ...
    | f269eebc-d86e-4cd0-aacc-8b0c53fb3bb2 | cloud-f17-x86_64              | SAVING | 4b3fccf9-28ab-4c29-acdb-cc5c18c862af |

Is there a way to do this properly?  Obviously I can just munge around
in the filesystem to do what I want, but I was hoping for something
more convenient.

I guess another option would be...

- Boot from the live CD
- Create a new volume
- Attach the volume
- Install onto the volume

Is it possible to snapshot an ephemeral disk?

-- 
Lars Kellogg-Stedman <lars at seas.harvard.edu>       |
Senior Technologist                                | http://ac.seas.harvard.edu/
Academic Computing                                 | http://code.seas.harvard.edu/
Harvard School of Engineering and Applied Sciences |





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