Error adding a Plain Volume created through GUI to Instance

Lee Yarwood lyarwood at redhat.com
Wed Sep 8 09:56:45 UTC 2021


On 06-09-21 11:41:03, Gorka Eguileor wrote:
> On 06/09, KK CHN wrote:
> > ExecutionError: Unexpected error while running command.
> > Command: rbd map volume-4dcb78d5-e0ce-4bfc-95ae-36a4417c35d8 --pool volumes
> > --id volumes --mon_host 10.236.223.131:6789 --mon_host 10.236.223.132:6789
> > Exit code: 6
> > Stdout: 'RBD image feature set mismatch. You can disable features
> > unsupported by the kernel with "rbd feature disable
> > volumes/volume-4dcb78d5-e0ce-4bfc-95ae-36a4417c35d8 journaling".\nIn some
> > cases useful info is found in syslog - try "dmesg | tail".\n'
> > Stderr: 'rbd: sysfs write failed\nrbd: map failed: (6) No such device or
> > address\n'
> >
> > I am trying to add a 20 GB plain volume created through Horizon GUI to an
> > existing Windows 2012 R  VM running with VirtIO drivers installed. But this
> > volume adding results in the error as shown above,
> >
> > trace tells to fix it by    rbd feature disable   ..   what is the
> > permanent fix for this issue ? and why it happens ?
> >
> > ( OpenStack Ussuri, Glance, Ceph , qemu-kvm)
> >
> > root at ctrl1:/home/cloud# ceph --version
> > ceph version 14.2.19 (bb796b9b5bab9463106022eef406373182465d11) nautilus
> > (stable)
> > root at ctrl1:/home/cloud#
> 
> Hi,
> 
> Usually RBD volumes are directly attached on the hypervisor, but there
> was an encryption performance issue [1] so nova and os-brick added
> support to attaching these volumes to the host and then use them on the
> VM.
> 
> Attaching volumes on the host uses the krbd module, whereas attaching
> them to the hypervisor directly uses librbd, with the first one lagging
> in terms of Ceph features.
> 
> The issue you are facing is that the images in RBD are being created
> with features that are not supported by krbd.
> 
> Fixes are:
> 
> - Disable those features in your ceph configuration file (usually
>   /etc/ceph/ceph.conf)
> 
>   Under [global] section add:
>      rbd default features = 3
> 
> - Change "[workarounds]rbd_volume_local_attach" to False in Nova's
>   config.
> 
> Cheers,
> Gorka.
> 
> [1]: https://bugzilla.redhat.com/show_bug.cgi?id=1762765
 
Yup thanks Gorka and just for awareness this workaround and the
associated disable_native_luksv1 workaround have been removed in the
Xena release as the underlying performance issues have been resolved
AFAIK:

workarounds: Remove rbd_volume_local_attach
https://review.opendev.org/c/openstack/nova/+/805648

workarounds: Remove disable_native_luksv1
https://review.opendev.org/c/openstack/nova/+/805647/

Cheers, 

-- 
Lee Yarwood                 A5D1 9385 88CB 7E5F BE64  6618 BCA6 6E33 F672 2D76
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