Re: block snapshot issue with RBD

[Jin Cao]

CC block and migration related address.

On 5/27/24 12:03 AM, Jin Cao wrote:
> Hi,
>
> I encountered RBD block snapshot issue after doing migration.
>
> Steps
> -----
>
> 1. Start QEMU with:
> ./qemu-system-x86_64 -name VM -machine q35 -accel kvm -cpu 
> host,migratable=on -m 2G -boot menu=on,strict=on 
> rbd:image/ubuntu-22.04-server-cloudimg-amd64.raw -net nic -net user 
> -cdrom /home/my/path/of/cloud-init.iso -monitor stdio
>
> 2. Do block snapshot in monitor cmd: snapshot_delete_blkdev_internal. It 
> works as expected: the snapshot is visable with command`rbd snap ls 
> pool_name/image_name`.
>
> 3. Do pseudo migration with monitor cmd: migrate -d exec:cat>/tmp/vm.out
>
> 4. Do block snapshot again with snapshot_delete_blkdev_internal, then I 
> get:
>     Error: Block format 'raw' used by device 'ide0-hd0' does not support 
> internal snapshots
>
> I was hoping to do the second block snapshot successfully, and it feels 
> abnormal the RBD block snapshot function is disrupted after migration.
>
> BTW, I get the same block snapshot error when I start QEMU with:
>      "-drive format=raw,file=rbd:pool_name/image_name"
>
> My questions is: how could I proceed with RBD block snapshot after the 
> pseudo migration?