[Openstack-operators] what is the different in use Qcow2 or Raw in Ceph

David Medberry openstack at medberry.net
Thu May 28 12:02:54 UTC 2015


and better explained here:
http://ceph.com/docs/master/rbd/qemu-rbd/

On Thu, May 28, 2015 at 6:02 AM, David Medberry <openstack at medberry.net>
wrote:

> The primary difference is the ability for CEPH to make zero byte copies.
> When you use qcow2, ceph must actually create a complete copy instead of a
> zero byte copy as it cannot do its own copy-on-write tricks with a qcow2
> image.
>
> So, yes, it will work fine with qcow2 images but it won't be as performant
> as it is with RAW. Also, it will actually use more of the native underlying
> storage.
>
> This is also shown as an Important Note in the CEPH docs:
> http://ceph.com/docs/master/rbd/rbd-openstack/
>
> On Thu, May 28, 2015 at 4:12 AM, Shake Chen <shake.chen at gmail.com> wrote:
>
>> Hi
>>
>> Now I try to use Fuel 6.1 deploy openstack Juno, use Ceph as cinder, nova
>> and glance backend.
>>
>> In Fuel document suggest if use ceph, suggest use RAW format image.
>>
>> but if I upload qcow2 image, seem working well.
>>
>> what is the different use qcow2 and RAW in Ceph?
>>
>>
>> --
>> Shake Chen
>>
>>
>> _______________________________________________
>> OpenStack-operators mailing list
>> OpenStack-operators at lists.openstack.org
>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
>>
>>
>
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