Cc'ing QCOW2 maintainer. ÕÅÓÑ¼Ó <zhang_you...@126.com> writes:
> Hi, > > I want to introduce a tiny tool(https://github.com/zhangyoujia/qcow2-dump) > for checking and repairing damaged qcow2 image. > > I met many damaged qcow2 images when I work. > > It does't always work by using the qemu-img command to check and repair these > damaged qcow2 images. > > The functions of the qemu-img check command are too limited for developers. > > It's difficult to known where is damaged, and difficult to repair the damage > too. > > For example: more than one active L2 entries point to the same active > cluster(mostly caused by refcount error), such as: > > Active Cluster: > ---------------------------------------------------------------- > REUSED cluster offset: 0x44000000 | l1_index: 2, l2_index: 1017 | > refcount: 2 > REUSED cluster offset: 0x44000000 | l1_index: 12, l2_index: 7780 > > REUSED cluster offset: 0x45000000 | l1_index: 2, l2_index: 1273 | > refcount: 2 > REUSED cluster offset: 0x45000000 | l1_index: 12, l2_index: 6742 > > REUSED cluster offset: 0x4a000000 | l1_index: 2, l2_index: 2553 | > refcount: 2 > REUSED cluster offset: 0x4a000000 | l1_index: 12, l2_index: 7068 > > The results of qemu-img check command are wrong which only show refcount > errors and copied errors, but do not show the active cluster reused errors. > so if you use qemu-img check -r sub-command to repair this qcow2 image, it > only increases refcount of the reused cluster, but does not rebuild the > reused active cluster. that does't work. (eg: reused_active_cluster.png) > > That's why I want to make a tool has more functions. > > qcow2-dump has some improvements compare with qemu-img check command: > > 1. -m check: output the status of qcow2 image and statistics of metadata. > (eg: rebuild_refcount_table.png) > > 2. -m error: output of -m check + the damaged positions of qcow2 image. (eg: > reused_active_cluster.png & error.tgz) > > 3. -m dump: output of -m error + dump all metadata of qcow2 image. (eg: > dump.tgz) > > > qcow2-dump also has some functions for repairing damaged qcow2 image: > > 1. rebuild damaged refcount table. (eg: rebuild_refcount_table.png) > qcow2-dump -R all rebuild_refcount_table.qcow2 > > 2. rebuild reused active cluster. (eg: reused_active_cluster.png) > qcow2-dump -R all -r reused_active_cluster.qcow2 > > 3. delete damaged qcow2 snapshot header. (eg: invalid_snapshot_header.png) > qcow2-dump -D snapshot[0] vm-disk-2.qcow2 > > 4. -m edit / -m copy: for repairing some special damage. (eg: comments of > qcow2_edit_modify is a instance) > > ... > > But this tool is not good enough yet, hope to receive your advices to improve > it. > > Best wishes > youplus
