On Wed, Sep 29, 2021 at 9:34 AM Vladimir Sementsov-Ogievskiy < vsement...@virtuozzo.com> wrote:
> Hi all! > > Recently we faced the following task: > > Customer comes and say: incremental backup images are too fat. Does you > incremental backup works correct? > > What to answer? We should check something. At least check that > incremental images doesn't store same data twice. And we don't have a > tool for it. I just wrote a simple python script to compare raw files > cluster-by-cluster. Then we've mounted the qcow2 images with help of > qemu-nbd, the resulting /dev/nbd* were compared and we proved that > incremental backups don't store same data. > > Good idea. I love diagnostic tools! > But that leads to idea that some kind of that script would be good to > have at hand. > > So, here is a new option for qemu-img compare, that is a lot more > powerful and effective than original script, and allows to compare and > calculate statistics, i.e. how many clusters differs, how many > clusters changed from unallocated to data, and so on. > > For examples of output look at the test in patch 04. > > Vladimir Sementsov-Ogievskiy (4): > qemu-img: implement compare --stat > qemu-img: make --block-size optional for compare --stat > qemu-img: add --shallow option for qemu-img compare --stat > iotests: add qemu-img-compare-stat test > > docs/tools/qemu-img.rst | 29 +- > qemu-img.c | 275 +++++++++++++++++- > qemu-img-cmds.hx | 4 +- > .../qemu-iotests/tests/qemu-img-compare-stat | 88 ++++++ > And new tests! :-) > .../tests/qemu-img-compare-stat.out | 106 +++++++ > 5 files changed, 484 insertions(+), 18 deletions(-) > create mode 100755 tests/qemu-iotests/tests/qemu-img-compare-stat > create mode 100644 tests/qemu-iotests/tests/qemu-img-compare-stat.out > > >
