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

[Alexandre DERUMIER]

>>Lack of bdrv_co_write_zeroes is why detect-zeroes does not work.
>>
>>Lack of bdrv_get_block_status is why sparse->sparse does not work
>>without detect-zeroes.

Ok, thanks Paolo !

Both are missing in rbd block driver. @ceph-devel . Could it be possible to 
implement them ?



Also, about drive-mirror, I had tried with detect-zeroes with simple qcow2 file,
and It don't seem to help.
I'm not sure that detect-zeroes is implement in drive-mirror.

also, the target mirrored volume don't seem to have the detect-zeroes option


# info block
drive-virtio1: /source.qcow2 (qcow2)
    Detect zeroes:    on

#du -sh source.qcow2 : 2M

drive-mirror  source.qcow2 -> target.qcow2

# info block
drive-virtio1: /target.qcow2 (qcow2)

#du -sh target.qcow2 : 11G




----- Mail original -----

De: "Paolo Bonzini" <address@hidden>
À: "Alexandre DERUMIER" <address@hidden>, "qemu-devel" <address@hidden>
Cc: "Ceph Devel" <address@hidden>
Envoyé: Dimanche 12 Octobre 2014 15:02:12
Objet: Re: qemu drive-mirror to rbd storage : no sparse rbd image

Il 08/10/2014 13:15, Alexandre DERUMIER ha scritto:
> 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.
>
>
> 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).

Lack of bdrv_co_write_zeroes is why detect-zeroes does not work.

Lack of bdrv_get_block_status is why sparse->sparse does not work
without detect-zeroes.

Paolo