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On Tue, 2021-07-27 at 10:29 +0100, Lee Yarwood wrote:
> On Tue, 27 Jul 2021 at 08:12, Ammad Syed <syedammad83 at gmail.com> wrote:
> > 
> > Hi,
> > 
> > I am using openstack wallaby. I am testing to evacuate instances from failed host.
> > 
> > The feature works fine. The instances on cinder backed shared storage rebuild on other host and their data is preserved. However the instances that are on local compute storage rebuild with fresh image on other host and data on root disk was lost.
yes so the evacutate api however should not be assumed to preserve data.
orginally it did not unless you mounted the nova instnace dir on nfs,
 latter support for preserving cinder volumes was added to the libvirt driver but by defalut
you shoudl assume that that instnace are rebuilt with a fresh image as that is the default behavior
if virt drivers dont opt in to preserving it.
 
strictly speakign the libvirt virt driver could decide to reimage the cinder volumes if it chose too but that is more work and would be
a worse user experence so we are never going to regess this but wether data is preserved is entirely dirver dependent.

> > 
> > The question is, is it possible to evacuate all instances from failed host that are on shared storage only ?
> > 
> > Ammad
> 
> No but that's a valid feature request IMHO, the current API is defined below:
> 
> https://docs.openstack.org/api-ref/compute/?expanded=evacuate-server-evacuate-action-detail#evacuate-server-evacuate-action

what woudl it look like. woudl we reust the old onSharedStorage flag in a new micorverion to mean evauate only if ion shared storage?
i think it might be more useful to extend the server show to contain if the server is on shared sotrage and then leave it up to the client
to evaucate the node or not. 

i dont really think we shoudl be extendeing the nova clinet host-evacuate commnad at this point since we are not gong to prot tha tot osc and evenutally
the nova client cli should be removed. i dont think we have formally deprecated or feature frozen nova client yet but since stephen updated osc to have
parity now i think we shoudl dicuss at the ptg is it time to deprecate it in yoga(just the cli part until sdk has partiy).

> Cheers,
> 
> Lee
> 
>