On 12/6/19 5:37 AM, Vladimir Sementsov-Ogievskiy wrote: > 06.12.2019 1:37, John Snow wrote: >> This has come up in the past, and I believe we discussed this at KVM >> Forum, too: >> >> There have been requests from oVirt (via Nir Soffer) to add some offline >> bitmap manipulation functionality. In the past, our stance has generally >> been "Use QEMU without an accelerator, and use QMP to manipulate the >> images." >> >> We like this for a few reasons: >> >> 1. It keeps bitmap management code tightly centralized >> 2. It allows for the full suite of bitmap manipulations in either >> offline or online mode with one tool >> 3. We wouldn't have to write new code. >> 4. Or design new CLIs and duplicate our existing work. >> 5. Or write even more tests. >> >> However, tools like oVirt may or may not be fully equipped to launch >> QEMU in this context, and there is always a desire for qemu-img to be >> able to "do more", so existing management suites could extend >> functionality more easily. > > I think, all guys, who don't want to use Qemu directly for image manipulations, > should hope for Kevin's "[RFC PATCH 00/18] Add qemu-storage-daemon", which is > the correct solution of their problem. Still, I'm not one of these guys. > >> >> (Or so I am imagining.) >> >> I am still leaning heavily against adding any more CLI commands or >> options to qemu-img right now. Even if we do add some of the fundamental >> ones like "add" or "remove", it seems only a matter of time before we >> have to add "clear", "merge", etc. Is this just a race to code duplication? >> >> On the other hand, one of the other suggestions is to have qemu-img >> check --repair optionally delete corrupted bitmaps. I kind of like this >> idea: it's a buyer beware operation that might make management layers >> unhappy, but then again ... repair is always something that could make >> things worse. >> >> Plus, if you manage to corrupt bitmaps badly enough that they can't even >> be parsed, you might need a heavyweight repair operation. >> > > Improving "check" is a correct thing, because it's done inside qcow2 driver > itself. We just don't have corresponding qmp command or command line option > for Qemu to use this thing (or I missed it). > OK, I agree. I made a redhat BZ to track that we want this: 1780416 - RFE: qemu-img check --repair should optionally remove any corrupted bitmaps I'll work on a patch and we can debate the details there. --js -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
