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#openstack-nova - 2017-04-19
15:17:24 dansmith namnh: that's why the docs say "or venv". You can apply the schema before you do anything, then shut down and upgrade your control services at the same time, then start on computes
15:17:27 dansmith mriedem: right
15:17:29 gcb mriedem, I have no idea why it fails randomly now
15:17:38 mriedem gcb: melwitt is going to re-write the test
15:18:39 gcb mriedem, good to know that, for the second issue, when the issue occurred ? From the Monday ?
15:18:45 mriedem namnh: see the 3rd bullet there which says "At this point, new columns and tables may exist in the database. These DB schema changes are done in a way that both the N and N+1 release can perform operations against the same schema."
15:19:07 mriedem namnh: meaning the schema changes are all additive and won't break old code running against them,
15:19:13 mriedem like any new column is always nullable
15:19:18 mriedem and we don't drop columns
15:20:14 namnh dansmith: so why we have to shutdown all nova services (except nova-compute)? due to RPC or something?
15:20:56 dansmith namnh: you only have to shut them down when you upgrade them, and all of them have to be shutdown together
15:21:13 dansmith namnh: what you can't have is nova-api and nova-scheduler on different *code* versions accessing the database at the same time
15:22:08 mriedem "For maximum safety (no failed API operations),"
15:22:40 dansmith it says that?
15:22:41 mriedem namnh: the control services have code in place to check versions of the computes since we support mixed level computes, but we don't for the control services
15:22:43 mriedem dansmith: yeah
15:22:44 dansmith that's not really the reason
15:22:55 mriedem see step 2 bullet 1
15:23:26 dansmith maybe that's easier to understand than the real reason, I dunno
15:24:17 namnh dansmith mriedem: if possible, could you give me an example for error when nova-api and nova-scheduler on different *code* versions accessing the database at the same time?
15:24:38 dansmith namnh: data corruption
15:24:48 dansmith seriously, don't do it
15:26:07 namnh dansmith: ok, I understood. Thanks for your time.
15:28:14 namnh mriedem: I just have understood. thanks
15:45:22 dr_gogeta86 hi
15:45:41 dr_gogeta86 how can I force a compute node up
15:45:41 dr_gogeta86 ?
15:45:52 dr_gogeta86 i've also rebooted many times but is always down
15:47:10 efried andymccr https://review.openstack.org/#/c/455710/12 - Pretty. So pretty.
15:47:36 imacdonn dr_gogeta86, I think you're supposed to ask questions like that (i.e. how to make it work, not regarding code development) in #openstack
15:47:57 imacdonn see topic ;)
15:48:01 dr_gogeta86 sorry
15:48:04 imacdonn np
15:48:05 efried dr_gogeta86 Yeah, what imacdonn said - but, check your n-cpu log
15:48:31 efried Sounds like compute service is failing to start or check in.
15:49:03 cdent efried: "save, like, five whole lines of code" <- my favorite review comment today, can hear it in my head
15:49:15 efried cdent :)
15:51:42 dr_gogeta86 efried, imacdonn tnx
15:51:55 mriedem cdent: to answer your question in the spec, i don't think we account for overheads when commiting the quota reservation
15:52:08 mriedem cdent: because the quota reservation is created in the api based on the flavor,
15:52:16 cdent mriedem: that's what I figured, thus my concern
15:52:21 cdent thanks for confirming it
15:52:22 mriedem cdent: then the reservation id for the quota is passed through to compute
15:52:30 mriedem and if the claim is good, we commit the reservation on the compute
15:52:34 mriedem but we don't modify it at all
15:53:07 cdent so if we make allocations be the true count, if they include overhead, user is going to be doing WTF sometimes
15:53:26 mriedem now that i say this, i don't see us passing reservations to build_and_run_instance
15:53:31 mriedem so i'm digging
15:53:31 cdent gyres within gyres
15:54:23 cdent what rough quota, its limit come round at last
15:56:48 mriedem cdent: so i was totally wrong
15:56:52 mriedem we commit the reservations in the api
15:56:59 mriedem in the _provision_instances method
15:57:19 cdent mriedem: that sounds like only partially wrong
15:57:29 mriedem either way we don't consider the overhead in the quota
15:57:33 mriedem quota usage i mean
15:57:46 mriedem had to fix that before melwitt dropped the 'quota usage' hammer on me
15:58:22 melwitt lol
15:59:05 cdent so many hammers, so few channels
16:00:00 mriedem ok, so yeah if we don't account for the overhead in the quota usage,
16:00:03 mriedem but we did in the allocation,
16:00:19 mriedem and we start using allocations (quota usage) for counting quotas stuff that mel is doing,
16:00:23 mriedem we're in a bind
16:01:01 mriedem because horizon shows me that i have 4GB of memory quota left, but the allocation is really 4GB + 256MB RAM
16:01:20 mriedem however, that's already the state we're in today
16:01:32 mriedem you're getting that extra overhead from the flavor w/o paying for it
16:02:04 mriedem if we account for the overhead in the allocations, and we use allocations for reporting quota, then we actually fix that hole don't we?
16:02:11 mriedem so you can bill your customers based on real usage?
16:02:45 cdent people will not like that change
16:02:51 mriedem define people
16:02:58 cdent end users
16:03:12 cdent "yesterday i was able to do X but today I can do x-1"
16:03:30 mriedem i imagine cloud providers would like it though
16:03:39 mriedem more cash for the utility company
16:03:43 cdent yeah, like tron or whatever, I fight for the users
16:04:30 mriedem cdent: just once, join evil corp
16:04:30 melwitt "we fixed the glitch"
16:04:59 mriedem bauzas: dansmith: jaypipes: i left a summary in the spec
16:05:02 mriedem https://review.openstack.org/#/c/437424/
16:05:06 cdent mriedem: I'm not sure I have any soul left to sell
16:05:11 jaypipes mriedem: danke
16:05:34 mriedem at a high level i feel like we should be accounting for the overhead (real usage) in the allocations
16:05:52 mriedem which would also benefit the initial select_destinations since placement has the whole story for actual allocations on a provider
16:05:59 hypothermic_cat lyarwood: hi, are you around?
16:06:44 lyarwood hypothermic_cat: hey, what's up?
16:06:51 mriedem i agree that over-estimating the reserved inventory buffer is an easier solution on us, but it also means operators have to be taking that into consideration now when configuring the comptues and doing capacity planning
16:07:11 cdent only if we don't automate it (through magic yet to be determined)
16:07:14 dansmith mriedem: unless we inflate the reserved amount ourselves
16:07:15 dansmith right
16:07:27 mriedem yeah i don't know how we do that yet
16:07:50 bauzas mriedem: okay, will read it
16:07:52 mriedem this is definitely fodder for the forum session on claims in the scheduler
16:07:56 bauzas and will try to make a new rev soon-ish
16:07:58 melwitt I don't remember what the "overhead" is. I've seen it before in the RT
16:08:10 mriedem melwitt: see estimate_instance_overhead in the virt drivers
16:08:19 melwitt or the virt driver
16:08:43 bauzas melwitt: don't put your foot into that ... :p
16:08:55 mriedem it's related to quota so melwitt has to put both feet in
16:08:56 melwitt I have before but then I forgot, so I guess I'm safe
16:08:58 bauzas or take the left one, if you want to be lucky

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