Open Stack

While I understand the general argument about pets versus cattle. The
question is, would you be willing to poke a few holes in the strict
"cattle" abstraction for the sake of pragmatism. Few shops are going
to make the direct transition in one move. Poking a hole in the cattle
abstraction allowing them to keep a pet VM might be very valuable to
some shops making a migration.

To be fair, the places where I've heard interest are looking to "walk
not run" from a pets approach to a cattle approach. This conceit in
the abstraction might be valuable enough to them to spell the
difference between cautiously adopting and tacitly rejecting
OpenStack.

That's how I would argue *for* the change anyhow, it's not an argument
based on ideology but on pragmatism.

On Mon, Mar 10, 2014 at 3:19 PM, Jay Pipes <jaypipes at gmail.com> wrote:
> On Mon, 2014-03-10 at 12:13 -0400, Shawn Hartsock wrote:
>> We have very strong interest in pursing this feature in the VMware
>> driver as well. I would like to see the revert instance feature
>> implemented at least.
>>
>> When I used to work in multi-discipline roles involving operations it
>> would be common for us to snapshot a vm, run through an upgrade
>> process, then revert if something did not upgrade smoothly. This
>> ability alone can be exceedingly valuable in long-lived virtual
>> machines.
>>
>> I also have some comments from parties interested in refactoring how
>> the VMware drivers handle snapshots but I'm not certain how much that
>> plays into this "live snapshot" discussion.
>
> I think the reason that there isn't much interest in doing this kind of
> thing is because the worldview that VMs are pets is antithetical to the
> worldview that VMs are cattle, and Nova tends to favor the latter (where
> DRS/DPM on vSphere tends to favor the former).
>
> There's nothing about your scenario above of being able to "revert" an
> instance to a particular state that isn't possible with today's Nova.
> Snapshotting an instance, doing an upgrade of software on the instance,
> and then restoring from the snapshot if something went wrong (reverting)
> is already fully possible to do with the regular Nova snapshot and
> restore operations. The only difference is that the "live-snapshot"
> stuff would include saving the memory view of a VM in addition to its
> disk state. And that, at least in my opinion, is only needed when you
> are treating VMs like pets and not cattle.
>
> Best,
> -jay
>
>> On Mon, Mar 10, 2014 at 12:04 AM, Bohai (ricky) <bohai at huawei.com> wrote:
>> >> -----Original Message-----
>> >> From: Alex Xu [mailto:xuhj at linux.vnet.ibm.com]
>> >> Sent: Sunday, March 09, 2014 10:04 PM
>> >> To: OpenStack Development Mailing List (not for usage questions)
>> >> Subject: Re: [openstack-dev] [nova] a question about instance snapshot
>> >>
>> >> Hi, Jeremy, the discussion at here
>> >> http://lists.openstack.org/pipermail/openstack-dev/2013-August/013688.html
>> >>
>> >
>> > I have a great interest in the topic too.
>> > I read the link you provided, and there is a little confusion for me.
>> > I agree with the security consideration in the discussion and memory snapshot can't be used for the cloning instance easily.
>> >
>> > But I think it's safe for the using for Instance revert.
>> > And revert the instance to a checkpoint is valuable for the user.
>> > Why we didn't use it for instance revert in the first step?
>> >
>> > Best regards to you.
>> > Ricky
>> >
>> >> Thanks
>> >> Alex
>> >> On 2014年03月07日 10:29, Liuji (Jeremy) wrote:
>> >> > Hi, all
>> >> >
>> >> > Current openstack seems not support to snapshot instance with memory and
>> >> dev states.
>> >> > I searched the blueprint and found two relational blueprint like below.
>> >> > But these blueprint failed to get in the branch.
>> >> >
>> >> > [1]: https://blueprints.launchpad.net/nova/+spec/live-snapshots
>> >> > [2]: https://blueprints.launchpad.net/nova/+spec/live-snapshot-vms
>> >> >
>> >> > In the blueprint[1], there is a comment,"
>> >> > We discussed this pretty extensively on the mailing list and in a design
>> >> summit session.
>> >> > The consensus is that this is not a feature we would like to have in nova.
>> >> --russellb "
>> >> > But I can't find the discuss mail about it. I hope to know why we think so ?
>> >> > Without memory snapshot, we can't to provide the feature for user to revert
>> >> a instance to a checkpoint.
>> >> >
>> >> > Anyone who knows the history can help me or give me a hint how to find the
>> >> discuss mail?
>> >> >
>> >> > I am a newbie for openstack and I apologize if I am missing something very
>> >> obvious.
>> >> >
>> >> >
>> >> > Thanks,
>> >> > Jeremy Liu
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > OpenStack-dev mailing list
>> >> > OpenStack-dev at lists.openstack.org
>> >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>> >> >
>> >> >
>> >> >
>> >>
>> >>
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>> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>>
>>
>>
>
>
>
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-- 
# Shawn.Hartsock - twitter: @hartsock - plus.google.com/+ShawnHartsock