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On 1/20/20 12:47 AM, Kim KS wrote:
> In nova with setting [cinder]/ cross_az_attach option to false, nova creates instance and volume in same AZ.
> 
> but some of usecase (in my case), we need to attach new volume in different AZ to the instance.
> 
> so I need two options.
> 
> one is for nova block device mapping and attaching volume
> and another is for attaching volume in specified AZ.
> 
>      [cinder]
>      cross_az_attach = False
>      enable_az_attach_list = AZ1,AZ2
> 
> how do you all think of it?

As Brin mentioned there are already config hacks in Cinder to workaround 
cross_az_attach issues between nova and cinder. cross_az_attach in nova 
is config-driven API behavior which is something to avoid if possible 
since it's not discoverable by the end user, so piling on more config 
complexity is something I'd try to avoid if possible. That option wasn't 
even very usable until recently [1].

Can you explain your use case a bit more? It sounds like you're trying 
to provide essentially default zones for nova/cinder if the server and 
volume are not created in a specific zone? Sort of similar to how the 
default_schedule_zone option in nova works if a server is created 
without a specific zone.

[1] 
https://github.com/openstack/nova/commit/07a24dcef7ce6767b4b5bab0c8d3166cbe5b39c0

--

Thanks,

Matt Riedemann