Re: [Qemu-devel] [PATCH V2 3/4] blockdev: Allow snapshoting of protocols.

[Eric Blake]

On 01/29/2013 07:27 AM, Benoît Canet wrote:
>> base1 [file] --- base1 [qcow2] --- snap1.qcow2 --\
>> base2 [file] --- base2 [qcow2] --- snap2.qcow2 --->-- quorum
>> base3 [file] --- base3 [qcow2] --- snap3.qcow2 --/

For that matter, I think it would be useful to have a quorum where the
data is duplicated between different formats, such as:

file1 [raw]                         --\
base2 [raw] --- snap2.qcow2 [qcow2] -->-- quorum
base3 [qed] --- snap3.qed [qed]     --/

In that case, you NEED to be able to pass in the protocol of each
underlying device _as part of opening the quorum_, something like:

quorum:2/3:file1[raw]:snap2.qcow2[qcow2]:snap3.qed[qed]

or some such punctuation.  And of course, that means you'd have to
extend your escaping mechanism to allow escaping of whatever syntax you
use for declaring a per-member format.

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

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