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. 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. v3: qemu-img: implement compare --stat fix wording fix option numbers allocate ImgCmpStat dynamically fix exit statuses restrict using strict mode together with --stat qemu-img: make --block-size optional for compare --stat fix wording qemu-img: add --shallow option for qemu-img compare fix option number(rebase on previous fix) add Hanna's r-b iotests: add qemu-img-compare-stat test add Hanna's r-b s/Agenda/Key/ in test output 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 iotests: add qemu-img-compare-stat test docs/tools/qemu-img.rst | 30 +- qemu-img.c | 275 +++++++++++++++++- qemu-img-cmds.hx | 4 +- .../qemu-iotests/tests/qemu-img-compare-stat | 88 ++++++ .../tests/qemu-img-compare-stat.out | 106 +++++++ 5 files changed, 485 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 -- 2.31.1
