Re: [Qemu-devel] RFC: handling image options with drive-mirror/drive-backup

[Kashyap Chamarthy]

On Thu, Sep 29, 2016 at 09:51:09AM +0100, Daniel P. Berrange wrote:
> On Thu, Sep 29, 2016 at 04:43:25PM +0800, Fam Zheng wrote:
> > On Thu, 09/29 09:34, Daniel P. Berrange wrote:

[...]

> > > So my suggestion is that we deprecate "drive-mirror" and define a fixed
> > > command "drive-mirror-blockdev" (or "blockdev-mirror" ?) that accepts
> > > the proper BlockdevOptions QAPI type for the target as above.
> > 
> > Are you aware that there is already a blockdev-mirror command? Supposedly it
> > can do what you need, together with blockdev-add once the latter is deemed
> > ready.
> 
> Clearly I'm not aware of that :-)  It seems libvirt does not yet use
> blockdev-mirror either, which is where I got the original bug report
> about drive-mirror from.
> 
> I'll submit a patch to mark drive-mirror as deprecated and point the
> otherwise ignorant reader towards blockdev-mirror instead....

You might also want to see this short thread I started last month to
clarify the semantics of `drive-mirror` & `blockdev-mirror`

    https://lists.nongnu.org/archive/html/qemu-block/2016-08/msg00472.html
    -- 'drive-mirror' vs. 'blockdev-mirror' semantics

Kevin's response to the above:

    https://lists.nongnu.org/archive/html/qemu-block/2016-08/msg00493.html

Some addendum to Kevin's response above:

    https://lists.nongnu.org/archive/html/qemu-block/2016-08/msg00503.html


And FWIW, here's some tests of `blockdev-add` + `blockdev-backup`
(`blockdev-mirror` is similar, just a different point-in-time --
point-in-time for 'drive-mirror' is when you break the synchronization;
and the point-in-time for 'drive-backup' is when you _start_ the
operation):

    
https://kashyapc.fedorapeople.org/virt/qemu/blockdev-add-and-blockdev-backup-success-tests.txt


-- 
/kashyap