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Date: Thu, 29 Sep 2016 17:09:20 +0800
From: Fam Zheng <famz@redhat.com>
Message-ID: <20160929090920.GB1118@lemon>
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Subject: Re: [Qemu-devel] RFC: handling image options with
 drive-mirror/drive-backup
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To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: qemu-devel@nongnu.org, kwolf@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>, qemu-block@nongnu.org

On Thu, 09/29 09:51, 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.

Libvirt doesn't support blockdev-add yet, because the command is still being
actively worked on at QEMU side, and is therefore thought to be not "stable"
yet. Though, I think blockdev-add + blockdev-{mirror,backup} are already useful
for common tasks (like your use case with LUKS).

> 
> I'll submit a patch to mark drive-mirror as deprecated and point the
> otherwise ignorant reader towards blockdev-mirror instead....

For above reasons, not sure whether we want to advertise it already.
Anyway deprecating drive-mirror is a bit too early.

Fam