Re: [Qemu-devel] KVM call agenda for June 28

[Marcelo Tosatti]

On Tue, Jun 28, 2011 at 02:38:15PM +0100, Stefan Hajnoczi wrote:
> On Mon, Jun 27, 2011 at 3:32 PM, Juan Quintela <address@hidden> wrote:
> > Please send in any agenda items you are interested in covering.
> 
> Live block copy and image streaming:
>  * The differences between Marcelo and Kevin's approaches
>  * Which approach to choose and who can help implement it

After more thinking, i dislike the image metadata approach. Management
must carry the information anyway, so its pointless to duplicate it
inside an image format.

After the discussion today, i think the internal mechanism and interface
should be different for copy and stream:

block copy
----------

With backing files:

1) base <- sn1 <- sn2
2) base <- copy

Without:

1) source
2) destination

Copy is only valid after switch has been performed. Same interface and
crash recovery characteristics for all image formats.

If management wants to support continuation, it must specify
blkcopy:sn2:copy on startup.

stream
------

1) base <- remote
2) base <- remote <- local
3) base <- local

"local" image is always valid. Requires backing file support.