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You can't just change the contents of a volume under the instance though -
at the very least you need to do an unmount in the instance, and a detach
is preferable, otherwise you've got data corruption issues.

At that point, the device naming problems are identical.

On 11 April 2016 at 20:22, Erlon Cruz <sombrafam at gmail.com> wrote:

> The actual user workflow is:
>
>  1 - User creates a volume(s)
>  2 - User attach volume to instance
>  3 - User creates a snapshot
>  4 - Something happens causing the need of a revert
>  5 - User creates a volume(s) from the snapshot(s)
>  6 - User detach old volumes
>  7 - User attach new volumes (and pray so they get the same id) - Nova,
> should have the ability to honor supplied device names (vdc, vdd, etc),
> which not always happen[1]. But, does the volume keep the same UUID in the
> system? Several application use that to boot.
>
> The suggested workflow would be simpler for a user POV:
>
>  1 - User creates a volume(s)
>  2 - User attach volume to instance
>  3 - User creates a snapshot
>  4 - Something happens causing the need of a revert
>  5 - User revert snapshot(s)
>
>
>  [1] https://goo.gl/Kusfne
>
> On Fri, Apr 8, 2016 at 5:07 AM, Ivan Kolodyazhny <e0ne at e0ne.info> wrote:
>
>> Hi Chenzongliang,
>>
>> I still don't understand what is difference between proposed feature and
>> 'restore volume from snapshot'? Could you please explain it?
>>
>> Regards,
>> Ivan Kolodyazhny,
>> http://blog.e0ne.info/
>>
>> On Thu, Apr 7, 2016 at 12:00 PM, Chenzongliang <chenzongliang at huawei.com>
>> wrote:
>>
>>> Dear Cruz:
>>>
>>>
>>>
>>>          Thanks for you kind support, I will review the previous spec
>>> according to the following links.  May be more user scenario we should
>>> considered,such as backup,create volume from snapshot,consistency group and
>>> etc,we will spend some time to gather
>>>
>>> the user's scenarios and determin what to do next step.
>>>
>>>
>>>
>>> Sincerely,
>>>
>>> zongliang chen
>>>
>>>
>>>
>>> *发件人:* Erlon Cruz [mailto:sombrafam at gmail.com]
>>> *发送时间:* 2016年4月5日 2:50
>>> *收件人:* OpenStack Development Mailing List (not for usage questions)
>>> *抄送:* Zhangli (ISSP); Shenhong (C)
>>> *主题:* Re: [openstack-dev] [Cinder] About snapshot Rollback?
>>>
>>>
>>>
>>> Hi Chen,
>>>
>>>
>>>
>>> Not sure if I got you right but I brought this topic in
>>> #openstack-cinder some days ago. The idea is to be able to rollback a
>>> snapshot in Cinder. Today what is possible to do is to create a volume from
>>> a snapshot. From the user point of view, this is not ideal, as there are
>>> several cases, if not the majority of, that the purpose of the snapshot is
>>> to revert to a desired state, and not keep the original volume. For some
>>> backends, keeping the original volume means space consumption. This space
>>> problem becomes bold when we think about consistency groups. For
>>> consistency groups, some backends might have to copy an entire filesystem
>>> for each snapshot, consuming space and time. So, I think it would be
>>> desired to have the ability to revert snapshots.
>>>
>>>
>>>
>>> I know there have been efforts in the past[1] to implement that, but for
>>> some reason the work was stopped. If you want to retake the effort please
>>> create a spec[2]  sol everybody can provide feedback.
>>>
>>>
>>>
>>> Erlon
>>>
>>>
>>>
>>>
>>>
>>> [1]
>>> https://blueprints.launchpad.net/cinder/+spec/cinder-volume-rollback-snapshot
>>>
>>> [2] https://github.com/openstack/cinder-specs
>>>
>>>
>>>
>>> On Thu, Mar 24, 2016 at 6:09 AM, Chenzongliang <chenzongliang at huawei.com>
>>> wrote:
>>>
>>> Hi all:
>>>
>>>     We are condering add a fucntion rollback_snapshot when we use
>>> backup. In the end user's scenario. If a vm fails, we hope that we can use
>>> snapshot to to recovery the volume's data.
>>>
>>>     Beacuse it can quickly recovery our vm. But if we use the remote
>>> data to recovery. We will spend more time.
>>>
>>>     But i'm not sure if the data was recoveried from the backend.
>>> whether the host need to rescan the volumes? At the same time. If a volume
>>> have been extended, whether it can be roolback?
>>>
>>>
>>>
>>>    I want to know whether the topic have been discussed or have other
>>> recommendations to us?
>>>
>>>
>>>
>>>    Thanks
>>>
>>>
>>>
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>>>
>>>
>>>
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>>
>
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-- 
-- 
Duncan Thomas
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