Open Stack

'metadata' is a free form key-value space for the tenant to use for
their own purposes - it has no semantic meaning to cinder. I expect
that other than adding filtering on metadata to the API (if it isn't
already there - I can't remember) that it will stay this way.

I take your point on the glance metadata. Glance has the concept to
mutable and immutable metadata, maybe we can do something with that?
I'll ask somebody who knows more about glance than me and get back to
you...

On 4 May 2014 10:33, Zhangleiqiang (Trump) <zhangleiqiang at huawei.com> wrote:
> Hi, stackers:
>
> I have some confusion about the respective use cases for volume's admin_metadata, metadata and glance_image_metadata.
>
> I know glance_image_metadata comes from image which is the volume created from, and it is immutable. Glance_image_metadata is used for many cases, such as billing, ram requirement, etc. And it also includes property which can effects the "use-pattern" of volume, such as volumes with "hw_scsi_mode=virtio-scsi" will be supposed that there is corresponding virtio-scsi driver installed and will be used as a device of "virtio-scsi" controller which has higher performance when booting from it with scsi bus type.
>
> However, volume is constantly having blocks changed, which may result in situations as follows:
>
> 1. A volume not created from image or created from image without "hw_scsi_mode" property at first but then has the virtio-scsi driver manually installed, there will be no method to make the volume used with virito-scsi controller when booting from it.
>
> 2. If a volume was created from an image with "hw_scsi_mode" property at first, and then the "virtio-scsi" driver in the instance is uninstalled, there will be no method to make the volume not used with "virtio-scsi" controller when booting from it.
>
> For the first situation, is it suitable to set corresponding metadata to volume? Should we use metadata or admin_metadata? I notice that volumes will have "attach_mode" and "readonly" admin_metadata and empty metadata after created, and I can't find the respective use cases for admin_metada and metadata.
>
> For the second situation, what is the better way to handle it?
>
> Any advice?
>
>
> ----------
> zhangleiqiang (Trump)
>
> Best Regards
>
>
>
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-- 
Duncan Thomas