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List:       ceph-devel
Subject:    Re: Snapshots of consistency groups
From:       Jason Dillaman <jdillama () redhat ! com>
Date:       2016-10-31 13:07:35
Message-ID: CA+aFP1ARgWp71xgqicF6vgx6Rd6kzYd-2mn1WPD9XtpQfO75=w () mail ! gmail ! com
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Looking at the Cinder codebase, I don't see any such restriction that
would prevent you from removing a volume from a consistency group that
has associated snapshots. I would double-check on the OpenStack
development mailing list if this is correct and is the intent. Worst
case, the RBD driver could raise an exception if there are still
consistency group snapshots associated to the image.


On Fri, Oct 28, 2016 at 6:41 PM, Victor Denisov <vdenisov@mirantis.com> wrote:
> Another thing that bothers me. When we remove an image from a consistency group.
> Should we remove all snapshots of this image that were created as part
> of a consistency group snapshot?
>
> The easiest solution would be to remove all snapshots that are in
> GroupSnapshotNamespace and reference this consistency group.
> I looked into cinder docs for this feature:
> http://docs.openstack.org/admin-guide/blockstorage-consistency-groups.html
>
> But it's not clear to me which behavior cinder expects.
>
> Thanks,
> V.
>
> On Wed, Oct 26, 2016 at 6:16 AM, Jason Dillaman <jdillama@redhat.com> wrote:
>> In a perfect world, it would be nice to add a new optional to "rbd
>> snap ls" to show all snapshots (with a new column to indicate the
>> associated namespace).
>>
>> On Tue, Oct 25, 2016 at 11:07 PM, Victor Denisov <vdenisov@mirantis.com> wrote:
>>> Question. When we print out snapshots of an image, should the group
>>> snapshots be listed, or should they be marked as special snapshots?
>>>
>>> Thanks,
>>> V.
>>>
>>> On Mon, Oct 10, 2016 at 3:14 PM, Victor Denisov <vdenisov@mirantis.com> wrote:
>>>> Ok. I didn't have any intention to throw exceptions.
>>>> I was more concerned about whether it's ok to allocate and delete
>>>> objects or I should use smart pointers.
>>>>
>>>> On Mon, Oct 10, 2016 at 7:18 AM, Jason Dillaman <jdillama@redhat.com> wrote:
>>>>> The only place exceptions are routinely used is within the "::decode"
>>>>> functions. I would prefer to see the code not throwing new exceptions
>>>>> on purpose.
>>>>>
>>>>> On Fri, Oct 7, 2016 at 2:26 PM, Victor Denisov <vdenisov@mirantis.com> wrote:
>>>>>> Are any exceptions used in librbd code? Should the code be exception safe?
>>>>>>
>>>>>> Thanks,
>>>>>> V.
>>>>>>
>>>>>> On Fri, Sep 16, 2016 at 10:37 AM, Jason Dillaman <jdillama@redhat.com> wrote:
>>>>>>> On Thu, Sep 15, 2016 at 7:17 PM, Victor Denisov <vdenisov@mirantis.com> wrote:
>>>>>>>> if (struct_v >= 5) {
>>>>>>>>       ::decode(snapshot_namespace, p);
>>>>>>>>     } else {
>>>>>>>>       snapshot_namespace = cls::rbd::UserSnapshotNamespace();
>>>>>>>>     }
>>>>>>>>
>>>>>>>> then code for ::encode function of cls_rbd_snap would change accordingly:
>>>>>>>>
>>>>>>>> instead of
>>>>>>>>
>>>>>>>> boost::apply_visitor(cls::rbd::EncodeSnapshotTypeVisitor(bl),
>>>>>>>> snapshot_namespace);
>>>>>>>>
>>>>>>>> I would do:
>>>>>>>> ::encode(snapshot_namespace, bl);
>>>>>>>
>>>>>>>
>>>>>>> +1 -- looks good to me
>>>>>>>
>>>>>>> --
>>>>>>> Jason
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Jason
>>
>>
>>
>> --
>> Jason



-- 
Jason
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