Copy Kevin.
On Wed, May 28, 2025 at 07:21:12PM +0530, Anushree Mathur wrote:
> Hi all,
>
>
> When I am trying to migrate the guest from host1 to host2 with the command
> line as follows:
>
> date;virsh migrate --live --domain guest1 qemu+ssh://dest/system --verbose
> --undefinesource --persistent --auto-converge --postcopy
> --copy-storage-all;date
>
> and it fails with the following error message-
>
> error: internal error: unable to execute QEMU command 'block-export-add':
> Block node is read-only
>
> HOST ENV:
>
> qemu : QEMU emulator version 9.2.2
> libvirt : libvirtd (libvirt) 11.1.0
> Seen with upstream qemu also
>
> Steps to reproduce:
> 1) Start the guest1
> 2) Migrate it with the command as
>
> date;virsh migrate --live --domain guest1 qemu+ssh://dest/system --verbose
> --undefinesource --persistent --auto-converge --postcopy
> --copy-storage-all;date
>
> 3) It fails as follows:
> error: internal error: unable to execute QEMU command 'block-export-add':
> Block node is read-only
>
> Things I analyzed-
> 1) This issue is not happening if I give --unsafe option in the virsh
> migrate command
>
> 2) O/P of qemu-monitor command also shows ro as false
>
> virsh qemu-monitor-command guest1 --pretty --cmd '{ "execute": "query-block"
> }'
> {
> "return": [
> {
> "io-status": "ok",
> "device": "",
> "locked": false,
> "removable": false,
> "inserted": {
> "iops_rd": 0,
> "detect_zeroes": "off",
> "image": {
> "virtual-size": 21474836480,
> "filename": "/home/Anu/guest_anu.qcow2",
> "cluster-size": 65536,
> "format": "qcow2",
> "actual-size": 5226561536,
> "format-specific": {
> "type": "qcow2",
> "data": {
> "compat": "1.1",
> "compression-type": "zlib",
> "lazy-refcounts": false,
> "refcount-bits": 16,
> "corrupt": false,
> "extended-l2": false
> }
> },
> "dirty-flag": false
> },
> "iops_wr": 0,
> "ro": false,
> "node-name": "libvirt-1-format",
> "backing_file_depth": 0,
> "drv": "qcow2",
> "iops": 0,
> "bps_wr": 0,
> "write_threshold": 0,
> "encrypted": false,
> "bps": 0,
> "bps_rd": 0,
> "cache": {
> "no-flush": false,
> "direct": false,
> "writeback": true
> },
> "file": "/home/Anu/guest_anu.qcow2"
> },
> "qdev": "/machine/peripheral/virtio-disk0/virtio-backend",
> "type": "unknown"
> }
> ],
> "id": "libvirt-26"
> }
>
>
> 3) Guest doesn't have any readonly
>
> virsh dumpxml guest1 | grep readonly
>
> 4) Tried giving the proper permissions also
>
> -rwxrwxrwx. 1 qemu qemu 4.9G Apr 28 15:06 guest_anu.qcow2
>
> 5) Checked for the permission of the pool also that is also proper!
>
> 6) Found 1 older bug similar to this, pasting the link for reference:
>
>
> https://patchwork.kernel.org/project/qemu-devel/patch/20170811164854.GG4162@localhost.localdomain/
>
>
>
> Thanks,
> Anushree-Mathur
>
>
--
Peter Xu
