Open Stack

This isn't remotely related to btrfs. It works fine with XFS. Not sure how
that works in Fuel, never used it.

On Thu, May 28, 2015 at 8:01 AM, Forrest Flagg <fostro.flagg at gmail.com>
wrote:

> I'm also curious about this.  Here are some other pieces of information
> relevant to the discussion.  Maybe someone here can clear this up for me as
> well.  The documentation for Fuel 6.0, not sure what they changed for 6.1,
> [1] states that when using Ceph one should disable qcow2 so that images are
> stored in raw format.  This is due to the fact that Ceph includes its own
> mechanisms for copy-on-write and snapshots.  According to the Ceph
> documentation [2], this is true only when using a BTRFS file system, but in
> Fuel 6.0 Ceph uses XFS which doesn't provide this functionality.  Also, [2]
> recommends not using BTRFS for production as it isn't considered fully
> mature.  In addition, Fuel 6.0 [3] states that OpenStack with raw images
> doesn't support snapshotting.
>
> Given this, why does Fuel suggest not using qcow2 with Ceph?  How can Ceph
> be useful if snapshotting isn't an option with raw images and qcow2 isn't
> recommended?  Are there other factors to take into consideration that I'm
> missing?
>
> [1]
> https://docs.mirantis.com/openstack/fuel/fuel-6.0/terminology.html#qcow2
> [2]
> http://ceph.com/docs/master/rados/configuration/filesystem-recommendations/
> [3]
> https://docs.mirantis.com/openstack/fuel/fuel-6.0/user-guide.html#qcow-format-ug
>
> Thanks,
>
> Forrest
>
> On Thu, May 28, 2015 at 8:02 AM, David Medberry <openstack at medberry.net>
> wrote:
>
>> 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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>>
>>
>
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