Re: [Qemu-devel] qemu drive-mirror to rbd storage : no sparse rbd image

[Fam Zheng]

On Wed, 10/08 13:15, Alexandre DERUMIER wrote:
> Hi,
> 
> I'm currently planning to migrate our storage to ceph/rbd through qemu 
> drive-mirror
> 
> and It seem that drive-mirror with rbd block driver, don't create a sparse 
> image. (all zeros are copied to the target rbd).
> 
> Also note, that it's working fine with "qemu-img convert" , the rbd volume is 
> sparse after conversion.

What is the source format? If the zero clusters are actually unallocated in the
source image, drive-mirror will not write those clusters either. I.e. with
"drive-mirror sync=top", both source and target should have the same "qemu-img
map" output.

Fam

> 
> 
> Could it be related to the "bdrv_co_write_zeroes" missing features in 
> block/rbd.c ?
> 
> (It's available in other block drivers (scsi,gluster,raw-aio) , and I don't 
> have this problem with theses block drivers).
> 
> 
> 
> Regards,
> 
> Alexandre Derumier
> 
> 
>