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#openstack-nova - 2018-01-29
15:50:46 efried not that it actually matters.
15:51:19 maciejjozefczyk jaypipes: so we should also check aggregation metadatas if there is already definition of allocation ratio defined?
15:51:42 maciejjozefczyk if zeros are in config?
15:51:50 jaypipes maciejjozefczyk: yeah. check out that operators mailing list thread I linked in there...
15:52:07 cdent efried: intra-cluster.
15:52:24 efried cdent So the thing is, we didn't have a way to model multiple providers before. Now we do. But it sounds to me like nested is *not* the multiple-provider model we want to use here. It just doesn't make sense in light of recently-merged capabilities for a single provider *or* tree to "own" inventory spanning more than one actual compute host. (Unless, as jaypipes implies, there's a memory sharing thing - we can talk abou
15:52:24 efried t that later.)
15:52:47 openstackgerrit Matt Riedemann proposed openstack/nova master: WIP: Add regression test wrinkle for rebuilding twice with invalid image https://review.openstack.org/538955
15:52:49 mriedem artom: ^
15:54:14 efried cdent If you do it in a single provider OR a tree, you'll always have to reconcile a request for some subset of the total resources that you can't actually satisfy from any one host.
15:54:16 artom mriedem, I think you'd have to get the server out of ERROR first
15:55:02 efried cdent With the single-provider model, which I gather is how it has needed to be done to this point, it sounds like some of that reconciliation was that max-unit hack.
15:55:20 jaypipes efried: yeah. I think it's a much better solution for vCenter to model their resource tracking in the vCenter virt driver in a similar fashion to how Ironic's virt driver works.
15:55:56 cdent efried: I have no issue with the inventory for hardware things being pushed all the way down the real hardware, but I _do_ think that representing the hierarchical relationships between things using a tool we've created that has hierarchy makes sense (in this case cluster->resource-pool->physical host)
15:56:27 jaypipes efried: that wouldn't *preclude* using nested providers if, say, certain compute nodes had PCI devices or NUMA nodes, etc. But I would use a new root provider for each compute node in the cluster and represent the cluster as a placement aggregate, not as a child node under a "fake root"
15:56:42 efried jaypipes ++ exactly
15:57:01 jaypipes cdent: I think we're mostly agreeing. just disagreeing on the "single root vs multiple roots" thing.
15:57:09 gibi mriedem: quick question: There is a bugfix https://review.openstack.org/#/c/525242 that needs rpc version bump. Is it something that needs to wait for Rocky?
15:57:24 efried cdent A placement tree is more than just a way to represent a hierarchy. It is also allows resource requests to span a tree. Which doesn't make sense in the vcenter model as I'm undestanding it.
15:57:52 mriedem artom: you can rebuild an ERROR server
15:58:05 cdent efried: then I think it probably hasn't been explained well enough
15:58:14 artom mriedem, hah, that makes it even easier to hit
15:58:29 mriedem gibi: that doesn't necessarily mean it has to wait for rocky,
15:58:35 mriedem gibi: but it does mean we wouldn't backport it
15:58:39 maciejjozefczyk jaypipes: I'm ok with the idea to check aggregation metadatas first
15:59:04 gibi mriedem: OK. Then I'm going to rebase the above patch
15:59:19 gibi mriedem: the backport impossibility was agreed earlier so that is clear
15:59:28 jaypipes maciejjozefczyk: ok. with your operator hat on, what do you think about my proposal, considering it involves a technically not backwards-compatible behaviour change?
15:59:59 efried cdent I think I get that logically, conductor < cluster <=> n-cpu < resource pool < compute hosts (right?) and from that perspective you want to be able to "model" that structure as a tree.
16:00:32 cdent efried, jaypipes: I'd be much better at this conversation if I wasn't still fighting off this cold, but it's not just the desired to model, there's also a desire to do some accounting
16:00:57 efried cdent 1 < many and 1 <=> 1
16:01:30 maciejjozefczyk jaypipes: From my perspective it would not change anyting, I set allocation_ratio per host not per aggregate, so my opinion seems not be helpful
16:01:46 jaypipes mgagne: hey! :)
16:02:00 mgagne jaypipes: hi!
16:02:07 jaypipes mgagne: we're talking about your favorite new anti-feature regarding host aggregates and allocation ratios :)
16:02:21 mgagne jaypipes: I just saw your email =)
16:02:39 jaypipes mgagne: cool. I'm hoping to commandeer maciejjozefczyk's patch to add this fix for you.
16:03:01 jaypipes of course, I'm trying to convince maciejjozefczyk that this would be of benefit ;)
16:03:04 mgagne jaypipes: I have yet to properly analyze your suggestion and related bug report.
16:03:22 jaypipes mgagne: no worries, would be good to get your feedback some time today.
16:03:39 jaypipes mgagne: I'm going to ping melwitt on it when she's up, too.
16:03:45 mgagne jaypipes: sure
16:04:00 sauloaugusto Is it possible to setup pike without cells ?
16:04:11 openstackgerrit Sen Yang proposed openstack/python-novaclient master: Implement hypervisor hostname exact patten match for server cold migrate https://review.openstack.org/520187
16:04:14 jaypipes sauloaugusto: nope.
16:04:56 efried cdent So I think where we're getting to is this: You could have your nice satisfying model, and have to hack the inventory distribution to make it work; or you could have a flatter model that's less closely representative of the "real world", but your inventorying is simple, and accounting flows automatically from scheduling/allocations.
16:05:25 efried cdent ...except for the part where vcenter is gonna move an instance from one host to another. Yeah, that gets a tad hairy without having done a real live migration or whatever.
16:05:40 sauloaugusto jaypipes: Is there any clue about the error when you migrate from a no cell env to pike and you can only list instances from admin tenant ?
16:06:39 dansmith sauloaugusto: that doesn't sound like a cells-related thing
16:07:30 dansmith (the cells code doesn't do anything special with users/tenants)
16:07:33 cdent efried: having allocations against physical hosts (instead of the cluster) cannot work because instances move and we've declared the virt driver is not allowed to manipulate allocations
16:07:56 efried cdent Yeah, I see where that's a problem. I don't have an answer for that.
16:08:08 cdent thus inventory on resource pools
16:08:17 efried and resultant hackage.
16:08:25 efried which is unfortunate.
16:08:32 maciejjozefczyk jaypipes mgagne: Need to go. Let me know in bug report about what you decided okey ;) I'll update the patch then
16:08:33 cdent because that is the level at which accounting is desired
16:08:43 jaypipes maciejjozefczyk: will do, thanks mate :)
16:09:49 efried cdent Well, at the very least the resource pools should not be children in the same tree. They should be roots.
16:10:15 openstackgerrit Matt Riedemann proposed openstack/nova master: Rollback instance.image_ref on failed rebuild https://review.openstack.org/538961
16:10:16 mriedem artom: here is the fix ^ let me know when you have an LP bug number so i can update the references in here
16:10:33 artom mriedem, yep, writing it up as we speak
16:11:02 cdent efried: remind me (because I'm half asleep) of the mechanism to go from a root (when in nova-scheduler) to the compute node where the spawn can be called?
16:11:14 sauloaugusto dansmith: I think that is related , because the error start after I do themigration steps from nova . After that I start to see the Can't upgrade a READER transaction to a WRITER mid-transaction error on nova-api.log .
16:11:20 cdent efried: if the root is in fact not that compute-monde
16:11:26 artom mriedem, so we're rolling back the image but not other things that could change, like keypair?
16:11:43 openstackgerrit Balazs Gibizer proposed openstack/nova master: Add regression test for bug 1735407 https://review.openstack.org/526095
16:11:45 openstack bug 1735407 in OpenStack Compute (nova) "[Nova] Evacuation doesn't respect anti-affinity rules" [Medium,In progress] https://launchpad.net/bugs/1735407 - Assigned to Balazs Gibizer (balazs-gibizer)
16:11:45 openstackgerrit Balazs Gibizer proposed openstack/nova master: Add late server group policy check to rebuild https://review.openstack.org/525242
16:11:48 mriedem artom: yeah - which was my original complaint in the earlier fix
16:12:03 dansmith sauloaugusto: the migration steps from no cells to one cell were required before pike
16:12:09 efried cdent Not sure we quite have that mechanism yet.
16:12:13 mriedem artom: we can't really roll everything back with what we have today in the conductor code
16:12:35 mriedem we'd either have to change the rpc cast to a call, or move the code that changes the instance from the api to conductor
16:12:37 cdent efried: indeed, thus why I've been modelling it the way I've been
16:12:40 efried cdent Yeah, a way to tie these brother-roots back to the compute host for purposes of allocation and deploy.
16:12:44 cdent if it is a child you know where to go
16:12:50 mriedem hell, maybe we should have just moved the instance.save() from api to conductor...
16:12:50 artom mriedem, yeah... I guess it's fine as a bandaid for now? Ideally we need to come back to this and fix it properly, maybe like what Andrey was proposing
16:12:52 cdent because
16:12:54 cdent it is a child
16:13:04 mriedem artom: yes this is a "tactical fix"
16:13:13 cdent a resource provider withing a compute-node is _obviously_ a child
16:13:22 efried cdent But if it's a child, the scheduler will happily deploy an instance with VCPU from pool1, MEMORY_MB from pool2, and DISK_GB from pool3.
16:13:24 cdent and it seems to me that the ironic model might be the thing that's weird
16:13:25 artom mriedem, heh, code for "someone else can deal with it once I'm retired" ;)
16:13:38 efried cdent Unless you *always* use a numbered granular group. Which doesn't seem like the right answer.
16:13:43 mriedem maybe - it's just something one of my old managers at ibm always said,
16:13:48 cfriesen jaypipes: for https://bugs.launchpad.net/nova/+bug/1742747 do we look at the cpu_allocation_ratio of the first host aggregate, or do we look for the first host aggregate that has cpu_allocation_ratio set?
16:13:49 openstack Launchpad bug 1742747 in OpenStack Compute (nova) "RT overrides default allocation_ratios for ram cpu and disk" [Undecided,In progress] - Assigned to Maciej Jozefczyk (maciej.jozefczyk)
16:13:54 mriedem "do we have a tactical fix while we work on the long-term strategic fix"
16:14:16 artom mriedem, not a bad way of thinking
16:14:26 efried I was doing a word puzzle the other day where the clue was "strategic" and the answer was "tactical". I thought how the IBM ppt-jockeys would flip out at that.
16:14:38 artom awaugama, you around? Since you're the cause of all this, if we build you our proposed tactical fix, you want to try and break it again?
16:14:39 sauloaugusto dansmith: Yes I did that, and I get get list o admin instances , and also create new instances at that . The problem that I can not do nothing at all other tenants .
16:14:53 artom Maybe if we let QE loose on it *before* merging it, we'll avoid the pain?
16:15:03 awaugama artom: I can do some sanity checks on it
16:15:09 mriedem artom: that never seems to happen
16:15:13 mriedem until it's in product
16:15:24 awaugama artom, and *Technically* I'm just the warning light, i'm not the cause of the issue

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