On Wed, Jun 12, 2019 at 9:50 AM Rafael Diaz Maurin
<Rafael.DiazMaurin@xxxxxxxxxxxxxxx> wrote:
>
> Hello Jason,
>
> Le 11/06/2019 à 15:31, Jason Dillaman a écrit :
> >> 4- I export the snapshot from the source pool and I import the snapshot
> >> towards the destination pool (in the pipe)
> >> rbd export-diff --from-snap ${LAST-SNAP}
> >> ${POOL-SOURCE}/${KVM-IMAGE}@${TODAY-SNAP} - | rbd -c ${BACKUP-CLUSTER}
> >> import-diff - ${POOL-DESTINATION}/${KVM-IMAGE}
> > What's the actual difference between the "rbd diff" outputs? There is
> > a known "issue" where object-map will flag an object as dirty if you
> > had run an fstrim/discard on the image, but it doesn't affect the
> > actual validity of the data.
>
>
> The feature discard=on is activated, and qemu-guest-agent is running on
> the guest.
>
> Here are the only differences between the 2 outputs of the "rbd diff
> --format plain" (image source and image destination) :
> Offset Length Type
> 121c121
> < 14103347200 2097152 data
> ---
> > 14103339008 2105344 data
> 153c153
> < 14371782656 2097152 data
> ---
> > 14369685504 4194304 data
> 216c216
> < 14640218112 2097152 data
> ---
> > 14638120960 4194304 data
> 444c444
> < 15739125760 2097152 data
> ---
> > 15738519552 2703360 data
>
> And the hashes of the exports are identical (between source and
> destination) :
> rbd -p ${POOL-SOURCE} export ${KVM-IMAGE}@${TODAY-SNAP} - | md5sum
> => ee7012e14870b36e7b9695e52c417c06
>
> rbd -c ${BACKUP-CLUSTER} -p ${POOL-DESTINATION} export
> ${KVM-IMAGE}@${TODAY-SNAP} - | md5sum
> => ee7012e14870b36e7b9695e52c417c06
>
>
> So do you think this can be caused by the fstrim/discard feature.
You said you weren't using fstrim/discard. If you export both images
and compare those image extents where the diffs are different, is it
just filled w/ zeroes?
> In fact, when fstrim/discard activated it, the only way to validate the
> export-diff is to compare full exports hashes ?
>
>
> Thank you.
>
>
> Best regards,
> Rafael
>
> --
> Rafael Diaz Maurin
> DSI de l'Université de Rennes 1
> Pôle Infrastructures, équipe Systèmes
> 02 23 23 71 57
>
>
--
Jason
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