[Openstack-operators] cinder volume_clear=zero makes sense with rbd ?

David Wahlstrom david.wahlstrom at gmail.com
Wed Nov 4 17:52:37 UTC 2015

Looking at the code in master (and ignoring tests), the only drivers I see
reference to volume_clear are the LVM and block device drivers:

$ git grep -l volume_clear

So other drivers (netapp, smb, gluster, and of course Ceph/RBD) simply
ignore this option (or more accurately, don't take any action).

On Wed, Nov 4, 2015 at 8:52 AM, Chris Friesen <chris.friesen at windriver.com>

> 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
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David W.
Unix, because every barista in Seattle has an MCSE.
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