Hi, I tried this with qemu-img version 1.0, Ubuntu 12.04 host and gentoo guest, with qcow2 disk image. This seems to work fine. Perhaps it was fixed in the new qemu-img versions.
shehbaz@BLAckArrOw:~$sudo dd if=/dev/nbd0 of=/dev/null bs=1M 8192+0 records in 8192+0 records out 8589934592 bytes (8.6 GB) copied, 185.003 s, 46.4 MB/s shehbaz@BLAckArrOw:~$ Did you try working with some other disk image? Did this issue get resolved already? Perhaps more information will be required to debug this now. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/583296 Title: I/O errors with qemu-nbd/qcow2 Status in QEMU: New Bug description: I tried to open a qcow2 file with qemu-nbd and backup the files in it. After some coping I get lot of I/O errors in dmesg and the system hangs. One time I got even a kernel panic (Of course on a productive Server ;-) ) How to reproduce: 1. Connect nbd to a qcow2 file, a virtual machine mustn't use this file: qemu-nbd --connect=/dev/nbd0 /mnt/qcow/andromeda.qcow2 2. Read some data from /dev/nbd0p1 dd if=/dev/nbd0p1 of=/dev/null bs=1M After a few Seconds till Minutes somethings crash's Attached some dmesg logs To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/583296/+subscriptions
