Re: [Qemu-devel] [PATCH 6/6] add mirroring to blockdev-transaction

[Eric Blake <eblake@redhat.com>]

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On 02/29/2012 06:37 AM, Paolo Bonzini wrote:
> Add a new transaction type, "mirror".  It stacks a new blkmirror
> file (instead of a snapshot) on top of the existing image.
> 
> It is possible to combine snapshot and mirror as two actions in the
> same transaction.  Because of atomicity ensured by blockdev-transaction,
> this will create a snapshot *and* ensure that _all_ operations that are
> sent to it are also mirrored.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  blockdev.c       |   47 +++++++++++++++++++++++++++++++++++------------
>  qapi-schema.json |   19 ++++++++++++++++++-
>  qmp-commands.hx  |   12 +++++++++++-
>  3 files changed, 64 insertions(+), 14 deletions(-)
> 

> @@ -721,6 +725,12 @@ actions array:
>        - "format": format of new image (json-string, optional)
>        - "reuse": whether QEMU should look for an existing image file
>          (json-bool, optional, default false)
> +      When "type" is "mirror":
> +      - "device": device name to snapshot (json-string)
> +      - "target": name of destination image file (json-string)
> +      - "format": format of new image (json-string, optional)
> +      - "reuse": whether QEMU should look for an existing image file
> +        (json-bool, optional, default false)

This falls out very nicely.

Do we want to also add a 'reopen' operation to the union, for the
remaining action needed by oVirt live migration?

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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