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#openstack-nova - 2019-03-08
17:20:28 mriedem no
17:20:29 dansmith omg
17:20:42 mriedem how about we just ping later
17:20:44 mriedem break
17:20:44 dansmith (the sound of a gunshot in oregon echoes through)
17:26:28 openstackgerrit Chris Friesen proposed openstack/nova master: Add emulated TPM support to Nova https://review.openstack.org/631363
17:39:39 fried_rice mriedem: I just added https://review.openstack.org/#/c/640879/ to https://etherpad.openstack.org/p/nova-stein-rc-potential -- is that a right thing?
17:40:05 mriedem that's not a regression right? it's latent since pike or queens?
17:40:21 fried_rice not a regression in stein, yes latent since several releases, will need to be backported there.
17:41:06 fried_rice so, not sure how that works; do we get it in now before rc and then backport it, or wait until stein is forked, drop it in master, wait for the dust to settle, then backport it to stable branches (including stein)?
17:41:28 mriedem technically if it's not a regression in stein it doesn't need to be stein-rc-potential (tag)
17:41:30 mriedem so the latter
17:41:36 mriedem if it's latent, we can fix it whenever and backport
17:42:16 mriedem ^ doesn't bar people from reviewing latent bug fixes before stein rc1 if they wnat
17:42:17 mriedem *want
17:42:38 mriedem just dont want to push anything in that is high risk if we don't need to
17:42:42 mriedem and i'm not saying this is high risk
17:42:45 mriedem i haven't looked it over
17:43:09 mriedem what i am saying is i'm going to lunch now
17:43:52 fried_rice thanks mriedem_burgers
19:03:11 artom mriedem_burgers, dansmith, back, ready when you are
19:04:35 dansmith I too am here
19:16:30 mriedem i'm back but
19:17:06 artom backbutt
19:17:23 dansmith as opposed to front butt?
19:18:21 mriedem gimme a minute
19:18:44 artom For what it's worth, revert https://review.openstack.org/#/c/595069/ + wait in compute manager is fine
19:18:54 artom Err, *I think that revert blah blah
19:19:21 mriedem https://hangouts.google.com/call/4MUfp6uNnY6ddII9gtXGAEEE
19:25:59 mriedem artom: see _get_neutron_events_for_live_migration for how live migration uses it
19:26:37 artom mriedem, ack
19:26:54 mriedem so i think we just wrap that around the migrate_instance_finish in finish_revert_resize
19:27:04 mriedem i'd probably split that code out to a new helper method for sanity..
19:37:42 artom Right, I gotta run again, I'll try to have those 2 patches up before the weekend
20:00:31 cfriesen so in devstack I'm running "nova migrate <uuid>" and I'm getting an error saying that it can't migrate to current host. Shouldn't it be disregarding the current host for migration?
20:03:45 dansmith cfriesen: do you only have one host?
20:03:52 cfriesen dansmith: nope, two
20:04:04 dansmith but I think you'll get that if the scheduler doesn't pick the other one as a candidate
20:04:08 cfriesen shed logs see it considering both right up till the weigher
20:04:23 cfriesen but for "migrate" we'd never want the current host
20:04:27 cfriesen only for resize
20:04:59 dansmith they're the same operation, so if allow-to-same is enabled, I think it'll allow it
20:06:10 openstackgerrit Michael Still proposed openstack/nova master: Make privsep.chown mocking for libvirt snapshot tests less magic. https://review.openstack.org/642134
20:06:12 cfriesen okay, but that makes no sense logically to the user. a "migrate" operation should mean moving it elsewhere.
20:06:40 dansmith cfriesen: yeah, I'm not arguing that it makes sense, I'm just stating what I think is the case
20:06:57 dansmith also, migrate is admin-only by default I think, so it might not get much visibility because of that
20:07:10 cfriesen I suspect you're right. but it means that with "resize on same host" enabled you currently have to explicitly specify a destination.
20:07:29 dansmith no,
20:07:37 cfriesen I'm pretty sure this is a regression, just not sure from when
20:07:41 dansmith it only means that if your current host is the most obvious target right?
20:08:03 cfriesen dansmith: okay, fair enough. it means you can't assume it won't land on the current host
20:08:30 dansmith I dunno how common it is to have allow-to-current enabled in production either
20:08:41 dansmith it was supposed to only be for gate testing
20:09:00 cfriesen It's useful in small clouds.
20:09:21 dansmith again, stating the original intent
20:09:24 cfriesen what was the rationale for defaulting it to "off"?
20:09:40 dansmith because it was only for testing
20:10:48 cdent tautology!
20:10:49 cfriesen I get that, but why was it only for testing? You're trying to resize, why would you force a migration too?
20:12:11 dansmith cfriesen: there were some reasons discussed originally when it was added, but it's been a long time.. probably mostly around how the major users of this stuff ran their clouds at the time
20:12:27 dansmith i.e. packing like flavors together
20:13:04 dansmith again, not saying it makes sense today, just saying why it was done that way
20:13:23 cfriesen currently I'd expect the scheduler to trigger it to move in that case
20:16:13 cfriesen anyways, reported it as a bug: https://bugs.launchpad.net/nova/+bug/1819216
20:16:13 openstack Launchpad bug 1819216 in OpenStack Compute (nova) "in devstack, "nova migrate <uuid>" will try to migrate to the same host (and then fail)" [Undecided,New]
20:19:16 mriedem did someone say resize to same host problems?! https://review.openstack.org/#/c/638791/
20:19:31 mriedem if you have servers in an affinity group, you can *only* resize to the same ohst
20:19:32 mriedem *host
20:19:58 mriedem cfriesen: there is also a bug for the thing you hit, semi-related anyway
20:20:38 cfriesen mriedem: right, I knew about the affinity group
20:20:51 mriedem the api says resize to same host, sure, but the compute says 'no way'
20:22:04 mriedem https://bugs.launchpad.net/nova/+bug/1811235
20:22:05 openstack Launchpad bug 1811235 in OpenStack Compute (nova) "instance's vm-state becomes error when cold-migrate instance to same host failed" [Medium,In progress] - Assigned to Matt Riedemann (mriedem)
20:23:07 mriedem the api check is here https://github.com/openstack/nova/blob/master/nova/compute/api.py#L3626
20:23:43 mriedem the compute check is here https://github.com/openstack/nova/blob/master/nova/compute/manager.py#L4287
20:24:04 mriedem which fails for everything except vmware
20:24:23 mriedem since vmware is a cluster and you can migrate within the same "host"
20:25:11 mriedem so allow_resize_to_same_host is true if you're doing a resize, but not a cold migration *unless* you've got vcenter
20:26:10 cfriesen arguably the scheduler should only allow cold migration to same host for vcenter
20:26:22 mriedem the scheduler doesn't know if it's vcenter
20:26:23 cfriesen I guess it's actually the conductor
20:26:27 mriedem or conductor
20:26:39 mriedem the control plane services are not supposed to know anything about the underlying compute driver
20:26:43 cfriesen can't we look at host capabilities or hypervisor type or something?
20:27:02 dansmith cfriesen: and make assumptions? what about vmware 2 which *can* do that thing.. it's a slippery slope
20:27:07 dansmith separation of responsibilities
20:27:11 cdent vmware even has a downstream patch which adds config for "always resize to same "host" "
20:28:19 mriedem cdent: that's kind of where https://review.openstack.org/#/c/638791/ is going
20:28:28 cfriesen how do we handle it for live migration?
20:28:50 mriedem we always ignore the source host
20:29:01 mriedem same for evac
20:29:18 cfriesen seems weird to make live migration and cold migration behave differently
20:31:47 mriedem so,
20:31:53 mriedem now that we report compute driver capabilities as traits,
20:31:56 mriedem and supports_migrate_to_same_host is a driver capability,
20:32:20 mriedem we could technically check the compute node provider traits for the source compute node from the api and determind if it supports cold migrate to the same host and filter the request spec appropriately
20:32:46 dansmith don't you need the opposite of that?
20:33:10 dansmith you need to know if it *needs* the same host for the vmware case, not whether not it *can* yeah?
20:33:57 mriedem yeah maybe, you can't cold migrate across clusters
20:33:59 mriedem right?

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