Hi,
in my installation I'm going to use volumes to boot instances, not
ephemeral disks. And I faced unexpected (for me, at least) behaviour
when trying to implement snapshoting: image, created with "openstack
server image create" can't be used for boot from volume, i.e.
I create image using "openstack server image create --name jsnap jex-n1"
and then:
- creating server using ephemeral disk
* openstack server create jTest [ ... ] --image jsnap
is *OK*
- creating server usingvolume, populated from image:
* openstack volume create jVol --size 8 *--image jsnap* --bootable
* openstack server create jTest [ ... ] --volume jVol
*FAIL**S* with the following error: "_Invalid image metadata. Error: A
list is required in field img_block_device_mapping, not a unicode (HTTP
400)_".
- creating server using volume, populated from snapshot (which
corresponds to the image):
* openstack volume create jVol --size 8 *--snapshot
f0ad0bf0-97f4-49df-b334-71b9eb639567* --bootable
* openstack server create jTest [ ... ] --volume jVol
is *OK*
Assuming this is correct (oh, really? can't find this topic in
documentation), I don't need image as it's senseless entity (I can't use
it for booting from volumes) and just need snapshot. But I still like
https://blueprints.launchpad.net/nova/+spec/quiesced-image-snapshots-with-qemu-guest-agent
so there are two questions regarding this:
1) whether the following sequence will do exactly the same as "server
image create" does? -
- "manually" freeze VM filesystem (using "guest-fsfreeze-freeze" command)
- create snapshot using "openstack volume snapshot create --volume
<volume name> --force <snapshot name>"
- "manually" unfreeze VM filesystem (using "guest-fsfreeze-thaw" command)
2) and, when using Cinder API, is there way to synchronously wait for
end of snapshot creation? It's useful in order to thaw filesystem
immediately after snapshot will be done - neither after nor before few
seconds.
Thanks.
--
Volodymyr Litovka
"Vision without Execution is Hallucination." -- Thomas Edison
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