Re: [Libguestfs] nbdkit: Could not read L1 table when reading exported qcow2

On Wed, Nov 21, 2018 at 11:33:33AM +0800, Han Han wrote: This creates a 1GB virtual size qcow2 (real size is about 196K): $ ll disk -rw-rw-r--. 1 rjones rjones 196624 Nov 21 09:20 disk $ file disk disk: QEMU QCOW Image (v3), 1073741824 bytes This exports the disk using the export name "raw". However nbdkit doesn't know anything about qcow2, so this exports bytes of qcow2 data to the client. The virtual size of the disk will be about 196K, and it won't be resizable (so you cannot write to it). Note that the -e (export name) option is not used by nbdkit so you don't need it. What precisely happens here is that qemu-img sees a qcow2 file and tries to read beyond the end of the file: nbdkit: file.2: error: invalid request: offset and count are out of range: offset=196608 count=512 If you want to export a qcow2 file, then it's better to use qemu-nbd since it knows about the qcow2 format: $ qemu-nbd -t disk & $ qemu-img info nbd://localhost image: nbd://localhost:10809 file format: raw virtual size: 1.0G (1073741824 bytes) disk size: unavailable Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html