Re: [Qemu-devel] [RFC V5 09/11] quorum: Add quorum_getlength().

[Eric Blake]

On 08/27/2012 01:30 AM, Benoît Canet wrote:
> Signed-off-by: Benoit Canet <address@hidden>
> ---
>  block/quorum.c |   24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)

Say I'm using a 2/3 quorum.  What happens if:

image A and B agree on initial content, but not length
image B and C agree on length, but not content

Does disagreeing with quorum consensus invalidate that member of the
quorum from influencing further decisions?  If there is a length
discrepancy, should we declare the quorum failed rather than relying on
a mere majority vote?  Or, if there is a length discrepancy, does
reading the contents beyond the end of the shorter files consider the
contents to be okay if the longer files have only NUL bytes in the extra
length?  I'm worried that you haven't fully thought through all the
scenarios here.

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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