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add pre-existing instances to nova database

asked 2019-10-08 11:40:13 -0600

jamesopst gravatar image

updated 2019-10-08 15:47:17 -0600

I have added a Rocky compute node to a new Stein environment. I can use it and create instances on it via Stein Openstack CLI. But the instances that were already on this compute node, before I moved it, do not appear in this new Stein environment.

Is there a way I can make Openstack "discover" those instances an add them to the Stein nova db and instance list?

thanks

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answered 2019-10-08 18:45:07 -0600

There is no such feature. Think about it: An instance is not an isolated object; it's connected to a network which doesn't exist in the Stein cloud, it might use volumes from the Rocky cloud. There may be other associations between the instance and objects in the Rocky cloud.

I would just snapshot the VMs (virsh snapshot-create-as in case you use a libvirt-based hypervisor), add the snapshots to the Glance catalog in your new Stein cloud and create new instances from them.

In case volumes are involved, they also need to be transferred to the Stein cloud. How this is done depends on the volume backends; Cinder has a volume manage API that allows importing existing LUNs, LVM logical volumes, RADOS block devices etc as volumes.

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thanks Bernd, you are right the more I thought about it the more I knew this wasn't a very plausible question. too many associations with the old cloud.

jamesopst gravatar imagejamesopst ( 2019-10-09 11:05:28 -0600 )edit

not plausible but also not impossible. would be a a cool feature no? "migrate between clouds" CLI would allow user to select new network, volume, etc from the new cloud. This would help with side by side version upgrades. it would alleviate the steps to snapshot, download, transfer, upload, recreate

jamesopst gravatar imagejamesopst ( 2019-10-09 11:10:29 -0600 )edit

Absolutely. You could even implement this as a shell script; it doesn't seem to require a lot of sophistication.

Bernd Bausch gravatar imageBernd Bausch ( 2019-10-09 21:15:07 -0600 )edit

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Asked: 2019-10-08 11:40:13 -0600

Seen: 42 times

Last updated: Oct 08