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On 7 May 2014 09:36, Trump.Zhang <zhangleiqiang at gmail.com> wrote:
> @Tripp, Thanks for your reply and info.
>
> I am also thinking if it is proper to add support for updating the volume's
> glance_image_metadta to reflect the "newest status" of volume.
>
> However, there may be alternative ways to achieve it:
> 1. Using the volume's metatadata
> 2. Using the volume's admin_metadata
>
> So I am wondering which is the most proper method.


We're suffering from a total overload of the term 'metadata' here, and
there are 3 totally separate things that are somehow becoming mangled:

1. Volume metadata - this is for the tenant's own use. Cinder and nova
don't assign meaning to it, other than treating it as stuff the tenant
can set. It is entirely unrelated to glance_metadata
2. admin_metadata - this is an internal implementation detail for
cinder to avoid every extension having to alter the core volume db
model. It is not the same thing as glance metadata or volume_metadata.

An interface to modify volume_glance_metadata sounds reasonable,
however it is *unrelated* to the other two types of metadata. They are
different things, not replacements or anything like that.

Glance protected properties need to be tied into the modification API
somehow, or else it becomes a trivial way of bypassing protected
properties. Hopefully a glance expert can pop up and suggest a way of
achieving this integration.