Sorry for a delay with an answer.
We were able to reproduce the issue in our lab so we investigated it, here is what we’ve found:
* First of all, libvirt doesn’t support RBD pools for backing volume disks out of the box [1]. There is a patch that adds it but it wasn’t merged [2] so it’s not an option here.
* CEPH volumes attached to libvirt according to CEPH official documentation [3], please note that it requires type=‘network’ in ‘disk definition.
* Actual failure occurs in libvirt in ‘virStorageFileBackendForTypeInternal’ function [4] because there is no item in ‘fileBackends’ that is of type ‘network’ and protocol ‘rbd’. Looking at definition of ‘fileBackends’ [5] it becomes clear that there is no support for that case too, since the only backend with type ‘network’ is ‘virStorageFileBackendGluster’.
So there is no way to gather disk usage data if RBD is used as backend.
Sorry for a delay with an answer.
We were able to reproduce the issue in our lab so we investigated it, here is what we’ve found:
* First of all, libvirt doesn’t support RBD pools for backing volume disks out of the box [1]. There is a patch that adds it but it wasn’t merged [2] so it’s not an option here.
* CEPH volumes attached to libvirt according to CEPH official documentation [3], please note that it requires type=‘network’ in ‘disk definition.
* Actual failure occurs in libvirt in ‘virStorageFile BackendForTypeI nternal’ function [4] because there is no item in ‘fileBackends’ that is of type ‘network’ and protocol ‘rbd’. Looking at definition of ‘fileBackends’ [5] it becomes clear that there is no support for that case too, since the only backend with type ‘network’ is ‘virStorageFile BackendGluster’ .
So there is no way to gather disk usage data if RBD is used as backend.
[1] https:/ /www.redhat. com/archives/ libvirt- users/2015- April/msg00001. html /www.redhat. com/archives/ libvir- list/2014- March/msg00107. html docs.ceph. com/docs/ hammer/ rbd/libvirt/ #configuring- the-vm libvirt. org/git/ ?p=libvirt. git;a=blob; f=src/storage/ storage_ backend. c;h=70d2a59cc85 7db1d4147e3d976 374cb6b7ed37eb; hb=09661a8e2910 d4f71ff0d55d0e8 6f8699c369bb9# l1209 libvirt. org/git/ ?p=libvirt. git;a=blob; f=src/storage/ storage_ backend. c;h=70d2a59cc85 7db1d4147e3d976 374cb6b7ed37eb; hb=09661a8e2910 d4f71ff0d55d0e8 6f8699c369bb9# l138
[2] https:/
[3] http://
[4] http://
[5] http://