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#openstack-nova - 2025-03-24
15:37:59 sean-k-mooney but i think thats where a lot of the end to end functial behaivor is verifed
15:38:24 sean-k-mooney https://github.com/openstack/placement/tree/master/placement/tests/functional/gabbits
15:39:01 sean-k-mooney there are a number of allcoation an dallcoation bug tests there for sepcifc beahivor
15:39:58 dansmith yeah,
15:40:13 dansmith but only one that explicitly tests overcapacity for allocations, AFAICT,
15:40:16 sean-k-mooney dansmith: i belive some of this is also enfoced at the db level althouhg i dont think they are usign db triggers or anything to actully encode it at the db level
15:40:21 dansmith and it's just the simplest case of asking for more than exists
15:40:32 dansmith sean-k-mooney: it is, and there's a single db test for one simple sccenario there
15:40:40 sean-k-mooney ack
15:40:50 dansmith I mean the db object layer in placement
15:41:00 sean-k-mooney i guess the assumtin is if you neever allow a simple allcotion to oversubscibe that covers the more advanced cases
15:41:03 dansmith there's a big complex function that checks if we're over capacity after an allocation
15:41:12 sean-k-mooney right
15:41:31 sean-k-mooney so https://github.com/openstack/placement/blob/master/placement/tests/functional/gabbits/allocations-bug-1779717.yaml#L73 is testing creating an allcotion for multiple consumers
15:41:38 dansmith it's not that simple though, that big function has a lot of edges that can't possibly be covered by a single test (single python test and a single gabbit test)
15:41:47 dansmith yep
15:42:07 sean-k-mooney although that is not really about capastiy
15:42:16 sean-k-mooney lookign at the bug itself https://bugs.launchpad.net/nova/+bug/1779717
15:43:15 sean-k-mooney i guess to un pick this a littel you might want to create a repoducer test for the current evac/cold migration case
15:43:21 sean-k-mooney where we are doing the swap
15:43:38 sean-k-mooney i suspect you can do that without gabit using the placement fixture
15:43:57 dansmith well, I want to test the underlying mechanics in placement, not nova
15:44:03 sean-k-mooney we certenly could do that in nova so i dont see why you could not in placment itself
15:44:09 dansmith and I expected to see a lot more coverage in placement given how complex the capacity check is
15:44:30 sean-k-mooney right but the the actial api behavior does not actully depend on nova
15:44:48 sean-k-mooney you jsut need to create the allcoation mess with reserved then try and swap it
15:45:01 sean-k-mooney basiclly emulate the OTU flow
15:45:32 sean-k-mooney i know you know that by the way im just trying to state the repoducer clearly
15:46:44 sean-k-mooney gabit is expressive enough to encode that but its not very deep coverage hench why you probly will want to try using the placement fixutre and writign a new functional test
15:46:59 dansmith yeah I'm very aware of what I need to do, I'm just surprised that there is so little coverage of this _area_ in placement
15:47:33 sean-k-mooney ill fully adming i have never been that deep on the implemation side of placement
15:47:39 sean-k-mooney only the usage of it
15:47:48 sean-k-mooney so i havent really looked tat the testing in any detail
15:47:52 dansmith okay I figured you and gibi are the most familiar, but maybe not
15:47:55 dansmith ack
15:48:25 sean-k-mooney gibi and melwitt i think. api wise yes but ptyhon wise less so on my part
15:48:50 sean-k-mooney im willing to review placement code but i generally need to learn the context every time i do
15:49:28 gibi dansmith: I would expect more than one over capacity test case. let me take a look
15:49:56 sean-k-mooney i think tis is the only functional testing of allctions https://github.com/openstack/placement/blob/master/placement/tests/functional/test_allocation.py
15:50:02 sean-k-mooney i.e. in python
15:50:10 dansmith I definitely want to do this in python functional tests and not gabbits, FWIW
15:51:20 sean-k-mooney dansmith: this is the one you wer referint too for the db level right https://github.com/openstack/placement/blob/master/placement/tests/functional/db/test_allocation.py#L519
15:51:51 sean-k-mooney a number of those functional tests are really like 5 tests in one
15:52:00 dansmith yup
15:52:24 dansmith yup, referring, but not sure yup in terms of coverage
15:52:30 dansmith the capacity check is very complex :)
15:53:20 sean-k-mooney https://github.com/search?q=repo%3Aopenstack/placement%20InvalidAllocationCapacityExceeded&type=code not that i realy turst github search but only 3 hits total
15:53:49 sean-k-mooney codesearch agrees
15:54:18 sean-k-mooney that excetion is not used elsewhere in the codebase
15:55:54 sean-k-mooney i guess there is also InvalidInventoryCapacity
15:56:18 sean-k-mooney but i think thats raised when you modify the inventory
15:56:38 dansmith right
15:56:52 gibi this file has some POST allocation tests https://github.com/openstack/placement/blob/master/placement/tests/functional/gabbits/allocations-post.yaml
15:57:19 gibi but I understand you want moe
15:57:20 gibi more
15:57:43 sean-k-mooney right and that does https://github.com/openstack/placement/blob/master/placement/tests/functional/gabbits/allocations-post.yaml#L212-L236
15:58:27 dansmith gibi: yeah it's not just allocation, it's allocation with the capacity check
15:58:35 dansmith *failing
15:59:16 gibi this also has some coverage https://github.com/openstack/placement/blob/master/placement/tests/functional/db/test_allocation.py but I'm not against adding more :)
16:04:17 dansmith that's really the only place in python, but yeah
16:07:05 gibi in cases when I'm not sure what is covered and not covered I tend to go in and break the code in certain cases to see if it caught be tests. Maybe there are test cases in wrongly named test files hiding
16:27:03 sean-k-mooney gibi: i dont think placement has the saem level fo in depth testing that nova has in genral. gabit is greate but often it was used instead of unit and functional testin instead of in addtion to them
16:27:57 sean-k-mooney one of the test case that i looked at was teh sole testing in the commit that added a new microverions
16:28:11 sean-k-mooney there may have been other changes in teh serise
16:28:39 sean-k-mooney but if that really was the only commit to implemnt the microversion it shows that gabbit testing was considered enough coverage for an api change
16:37:35 dansmith gibi: yeah I was going to create a reproducer for the issue and then break it to make sure it starts working.. so I guess we'll see if something stops when I do :)
16:44:27 simondodsley hi - i'm looking for advice on how to disable `discard` on a single cinder volume that is coming from a cinder driver where `discard` is hardcoded to be `True`. A customer is having issues with multiattach volumes that they want to use for Windows clustering, in that the SCSI page 83h doesn't appear to be passing through the SCSI reservation settings.
16:45:29 simondodsley I read that `nodiscard` may resolve this, but can't work out how to do the override. Overriding the whole backend for a test would be an option, but as I say the cinder driver has `disacrd` hardcoded. Is there somethin in nova that can help?
16:46:40 sean-k-mooney simondodsley: so windwos clustering required the vm to be create with a volume configured to use type=lun which cant be set durign attach only vm creation
16:46:47 dansmith yep, was just going to say ^
16:47:01 sean-k-mooney we shoudl probaly fix that at some point
16:47:13 sean-k-mooney but anyway i am not sure if you can overried that with our libvirt section
16:47:17 dansmith is that enough to enable it? I thought not
16:47:25 sean-k-mooney we have a cofnig option for discard but i tought it was for nova provisioend storage
16:47:27 dansmith I thought lun was the only way
16:47:43 sean-k-mooney no i think you need lun for scsi v3
16:47:49 simondodsley so how do we set the type=lun at vm creation?
16:47:57 sean-k-mooney i just ment that even behond that im not sure if you can overried discard form nova
16:49:03 sean-k-mooney simondodsley: so the only discard cofnig im awre of in nova is https://docs.openstack.org/nova/latest/configuration/config.html#libvirt.hw_disk_discard which woudl turn it off for the host but that says "nova managed disks"
16:49:18 dansmith sean-k-mooney: I think if they want the guest to use discard and have that make it all the way to the actual physical device they need to use lun, no?
16:49:47 sean-k-mooney dansmith: well that what will happen if discard is enabeld on the cinder volume in the connection info
16:49:54 dansmith I thought libvirt discard would only hit the qemu storage driver, like ceph or qcow2
16:50:19 sean-k-mooney dansmith: i guess there are two diffent things happenign here
16:50:51 sean-k-mooney simondodsley made the assertion that truning of discard migh help with the scsi command making it to the backend. i think we both agree it not related to that
16:51:05 dansmith tight
16:51:11 dansmith *right :)
16:51:25 sean-k-mooney simondodsley: so if you look at the server create api https://docs.openstack.org/api-ref/compute/#create-server
16:52:10 sean-k-mooney there is an option device_type filed in the request
16:52:17 sean-k-mooney in the block device mappings
16:52:50 sean-k-mooney sorry that might not be the correct filed
16:53:03 sean-k-mooney i think you want block_device_mapping_v2.disk_bus i will neeed to check the other doc
16:53:25 sean-k-mooney https://docs.openstack.org/nova/latest/user/block-device-mapping.html
16:53:40 sean-k-mooney ok no so you want disk_bus=scsi and deivce_type=lun
16:54:02 sean-k-mooney """disk_bus and device_type - low level details that some hypervisors (currently only libvirt) may support. Some example disk_bus values can be: ide, usb, virtio, scsi, while device_type may be disk, cdrom, floppy, lun. This is not an exhaustive list as it depends on the virtualization driver, and may change as more support is added. Leaving these empty is the most common
16:54:04 sean-k-mooney thing to do."""
16:54:48 simondodsley ok - so how would that be forced from the comand line, or the gui?
16:55:01 sean-k-mooney you cant do it form horizon
16:55:12 sean-k-mooney from the cli you an do it when creating the block device mapppings
16:55:32 sean-k-mooney https://docs.openstack.org/python-openstackclient/latest/cli/command-objects/server.html#server-create
16:55:54 sean-k-mooney you have to use teh --block-device parmater instead of --volume

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