[libvirt] [PATCH 1/2] rbd: Implement wiping RBD volumes using rbd_discard()

[Wido den Hollander]

On 23-12-15 10:45, Daniel P. Berrange wrote:
> On Wed, Dec 23, 2015 at 10:29:04AM +0100, Wido den Hollander wrote:
>> This allows user to use the volume wiping functionality of the libvirt
>> storage driver.
>>
>> All data from the volume will be wiped by calling rbd_discard() in chunks of the
>> underlying object and stripe size inside Ceph.
>>
>> This will ensure all data is zeroed and leaves the user with a completely empty volume
>> ready for use again.
> 
> Based on the name 'rbd_discard' it sounds like this is going to call
> TRIM/DISCARD on the underlying storage too ? If so, then I don't think
> that this is an appropriate approach for this API. The virStorageVolWipe
> API should clear the data, *without* having any effect on the storage of
> the API - ie we don't want to discard underling storage blocks as a
> side effect
> 

Afaik it zeroes/trims all the RBD objects on the Ceph cluster, but it
doesn't TRIM the lower SSD on it's turn.

So it will send these calls to Ceph/RBD and it will zero all the data of
that specific volume. A rather simple way to get rid of the data in a
volume.

If makes sure that the volume no longer contains any data for the
end-user. All user-data on the volume will be gone.

Or am I misunderstanding you? What is it supposed to do?

Wido

> 
> Regards,
> Daniel
>