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On 11/04/2015 08:46 AM, Saverio Proto wrote:
> Hello there,
>
> I am using cinder with rbd, and most volumes are created from glance
> images on rbd as well.
> Because of ceph features, these volumes are CoW and only blocks
> different from the original parent image are really written.
>
> Today I am debugging why in my production system deleting cinder
> volumes gets very slow. Looks like the problem happens only at scale,
> I can't reproduce it on my small test cluster.
>
> I read all the cinder.conf reference, and I found this default value
> =>   volume_clear=0.
>
> Is this parameter evaluated when cinder works with rbd ?

I don't think that's actually used with rbd, since as you say Ceph uses CoW 
internally.

I believe it's also ignored if you use LVM with thin provisioning.

Chris