[cinder] ceph multiattach details?

Martinx - ジェームズ thiagocmartinsc at gmail.com
Mon May 27 21:31:29 UTC 2019


Hello,

 I'm very curious about this as well!

 It would be awesome to support Cinder multi-attach when using Ceph... If
the code is already there, how to use it?!

Cheers,
Thiago

On Mon, 27 May 2019 at 03:52, Bernd Bausch <berndbausch at gmail.com> wrote:

> The Stein release notes mention that the RBD driver now supports
> multiattach, but i have not found any details. Are there limitations? Is
> there a need to configure anything?
>
> In the RBD driver
> <https://opendev.org/openstack/cinder/src/branch/master/cinder/volume/drivers/rbd.py#L767>,
> I find this:
>
>     def _enable_multiattach(self, volume):
>         multipath_feature_exclusions = [
>             self.rbd.RBD_FEATURE_JOURNALING,
>             self.rbd.RBD_FEATURE_FAST_DIFF,
>             self.rbd.RBD_FEATURE_OBJECT_MAP,
>             self.rbd.RBD_FEATURE_EXCLUSIVE_LOCK,
>         ]
>
> This seems to mean that journaling and other features (to me, it's not
> quite clear what they are) will be automatically disabled when switching on
> multiattachment.
>
> Further down in the code I see that replication and multiattach are
> mutually exclusive.
>
> Is there some documentation about the Ceph multiattach feature, even an
> email thread?
>
> Thanks,
>
> Bernd
>
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