[libvirt-users] Create multiple domains from single saved domain state (is UUID/name fixed?)

Jonas Finnemann Jensen jonasfj at mozilla.com
Mon Apr 18 18:49:09 UTC 2016


Hi,

I would like to save a running domain (ie. disk + memory) and be able to
restore it multiple times creating duplicates of the orignal domain all
starting from the same state.
Use case:
I'm building a task-processing system for use in a CI flow.
I want to run multiple VMs in parallel using the same image (always
starting from the same state).
And to avoid needlessly booting between each task, I would like to save
(and distribute) the domain state, so that I just restore from memory.

However, I can't seems to change the UUID or the name of a domain once it
is saved.
Nor do I seem able to rename a domain while it is running.

I can obviously duplicate both the disks and the file to which I saved the
domain state using "virsh save".
But I seem unable to rename before I restore.. Any ideas?

Could I do this with snapshots? I suspect not since I see
virDomainSnapshotRedefinePrep() calling
virDomainDefCheckABIStability which raises the error here:
https://fossies.org/dox/libvirt-1.3.3/domain__conf_8c_source.html#l17991

Out of curiosity does anyone know what horrors might befall me if I were to
remove the lines protecting against name and UUID changes? Then compile my
own libvirt...
The comment in the code says name can be changed, but I'm guessing I would
have to change the UUID too. Does anyone see how that would create issues?
I'm not sure how libvirt uses the UUID internally.

--
Regards Jonas Finnemann Jensen.
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