Re: [Qemu-devel] [PATCH 1/3] block: allow migration to work with image files

[Anthony Liguori]

On 09/12/2010 05:37 AM, Avi Kivity wrote:
>  On 09/11/2010 05:04 PM, Anthony Liguori wrote:
> > Image files have two types of data: immutable data that describes 
> > things like
> > image size, backing files, etc. and mutable data that includes offset 
> > and
> > reference count tables.
>
> Note: even the logical size is, in principle, mutable.  If we 
> introduce external snapshots, then so are backing files?

Maybe it should be, "data the can be changed during a live migration".

Backing files and logical size shouldn't change during live migration.

But even so, I think the interface make sense.  It's basically, drop 
anything you have cached that may change during migration.  What needs 
to be read is dependent on features/format.

Regards,

Anthony Liguori