I am facing an issue while using qemu-nbd thinly-provisioned exported qcow2 disk.
below is the steps:
1. qemu-img create -f qcow2 /tmp/img.qcow2 100M
2. qemu-nbd -f raw /tmp/img.qcow2
3. then I use it as a virtual disk in guest vm with xml like below:
<disk type='network' device='disk'>
<driver name='qemu' type='qcow2'/>
<host name='xxx.xxx.xxx.xxx' port='10809'/>
<target dev='sda' bus='scsi'/>
4. when i start the guest and try to format it in the guest, I got the error:
blk_update_request: critical target error, dev sda, sector 204672 op 0x1:(WRITE) flags 0x800 phys_seg 16 prio class 0
but I tried with the disk image created with full allocated by command:
qemu-img create -f qcow2 /tmp/img.qcow2 100M -o preallocation=full
then there is no error, so I assume it is related to the thinly-provisioned feature.
I am using: qemu-kvm-6.1.0, libvirt-7.8.0 on Red Hat Enterprise Linux release 8.6 Beta
So can you kindly help to confirm whether the thinly-provisioned cause the error?
and if so, are there any plan to fix or add new feature for it?
I am looking forward to your reply, thx.