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 <jaypi...@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) <bo...@huawei.com> wrote: >> >> -----Original Message----- >> >> From: Alex Xu [mailto:x...@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@lists.openstack.org >> >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> >> > >> >> > >> >> > >> >> >> >> >> >> _______________________________________________ >> >> OpenStack-dev mailing list >> >> OpenStack-dev@lists.openstack.org >> >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> > _______________________________________________ >> > OpenStack-dev mailing list >> > OpenStack-dev@lists.openstack.org >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> >> >> > > > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev -- # Shawn.Hartsock - twitter: @hartsock - plus.google.com/+ShawnHartsock _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
