For LVM-thin I believe it is already disabled? It is only really
needed on LVM-thick, where the returning zeros behaviour is not done.

On 21 October 2014 08:29, Avishay Traeger <avis...@stratoscale.com> wrote:
> I would say that wipe-on-delete is not necessary in most deployments.
>
> Most storage backends exhibit the following behavior:
> 1. Delete volume A that has data on physical sectors 1-10
> 2. Create new volume B
> 3. Read from volume B before writing, which happens to map to physical
> sector 5 - backend should return zeroes here, and not data from volume A
>
> In case the backend doesn't provide this rather standard behavior, data must
> be wiped immediately.  Otherwise, the only risk is physical security, and if
> that's not adequate, customers shouldn't be storing all their data there
> regardless.  You could also run a periodic job to wipe deleted volumes to
> reduce the window of vulnerability, without making delete_volume take a
> ridiculously long time.
>
> Encryption is a good option as well, and of course it protects the data
> before deletion as well (as long as your keys are protected...)
>
> Bottom line - I too think the default in devstack should be to disable this
> option, and think we should consider making the default False in Cinder
> itself.  This isn't the first time someone has asked why volume deletion
> takes 20 minutes...
>
> As for queuing backup operations and managing bandwidth for various
> operations, ideally this would be done with a holistic view, so that for
> example Cinder operations won't interfere with Nova, or different Nova
> operations won't interfere with each other, but that is probably far down
> the road.
>
> Thanks,
> Avishay
>
>
> On Tue, Oct 21, 2014 at 9:16 AM, Chris Friesen <chris.frie...@windriver.com>
> wrote:
>>
>> On 10/19/2014 09:33 AM, Avishay Traeger wrote:
>>>
>>> Hi Preston,
>>> Replies to some of your cinder-related questions:
>>> 1. Creating a snapshot isn't usually an I/O intensive operation.  Are
>>> you seeing I/O spike or CPU?  If you're seeing CPU load, I've seen the
>>> CPU usage of cinder-api spike sometimes - not sure why.
>>> 2. The 'dd' processes that you see are Cinder wiping the volumes during
>>> deletion.  You can either disable this in cinder.conf, or you can use a
>>> relatively new option to manage the bandwidth used for this.
>>>
>>> IMHO, deployments should be optimized to not do very long/intensive
>>> management operations - for example, use backends with efficient
>>> snapshots, use CoW operations wherever possible rather than copying full
>>> volumes/images, disabling wipe on delete, etc.
>>
>>
>> In a public-cloud environment I don't think it's reasonable to disable
>> wipe-on-delete.
>>
>> Arguably it would be better to use encryption instead of wipe-on-delete.
>> When done with the backing store, just throw away the key and it'll be
>> secure enough for most purposes.
>>
>> Chris
>>
>>
>>
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-- 
Duncan Thomas

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