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.fl...@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 <openst...@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 <openst...@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.c...@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@lists.openstack.org >>>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators >>>> >>>> >>> >> >> _______________________________________________ >> OpenStack-operators mailing list >> OpenStack-operators@lists.openstack.org >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators >> >> >
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