Bug 1801931

Summary: max_disk_devices_to_attach set to 0 don't allow to create any instance
Product: Red Hat OpenStack Reporter: jpateteg
Component: openstack-novaAssignee: melanie witt <mwitt>
Status: CLOSED ERRATA QA Contact: OSP DFG:Compute <osp-dfg-compute>
Severity: medium Docs Contact:
Priority: medium    
Version: 16.0 (Train)CC: dasmith, eglynn, igallagh, jhakimra, kchamart, mwitt, rheslop, sbauza, sgordon, vromanso
Target Milestone: betaKeywords: Triaged
Target Release: 17.0   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: openstack-nova-22.1.0-0.20210129121939.900fd51.el8ost Doc Type: Bug Fix
Doc Text:
Before this update, the help text for the `max_disk_devices_to_attach` parameter did not state that `0` is an invalid value. Also, when the `max_disk_devices_to_attach` parameter was set to `0`, the `nova-compute` service started when it should have failed. With this update, the `max_disk_devices_to_attach` parameter help option text states that a value of `0` is invalid, and if `max_disk_devices_to_attach` is set to `0`, the `nova-compute` service will now log an error and fail to start.
Story Points: ---
Clone Of:
: 1924406 (view as bug list) Environment:
Last Closed: 2022-09-21 12:09:13 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1924406, 1924407    

Description jpateteg 2020-02-11 23:17:26 UTC
Description of problem:

When the variable max_disk_devices_to_attach is set to 0 (documentation indicates it accepts >=0) it won't allow to create any instances in any compute node. This will prevent customer of creating any instance.


Version-Release number of selected component (if applicable):
openstack-nova-compute:16.0-80

How reproducible:
set the max_disk_devices_to_attach to 0 in nova.conf and create any instance

Steps to Reproduce:
1- Create a yaml file containing:

parameter_defaults: 
  ComputeExtraConfig:
    nova::config::nova_config:
      compute/max_disk_devices_to_attach:
       value: '"0"'

2- Deploy the overcloud
3- Create an instance

Actual results:
Instance is not created. The following error message appears:

'code': 500, 'created': '2020-02-11T19:54:07Z', 'message': 'Build of instance a43020ca-de89-4082-9beb-52cefe9905a6 aborted: The maximum allowed number of disk devices (0) to attach to a single instance has been exceeded.'

Expected results:
- Instance to be created with at least one root device to allow boot.

OR

- Indicate in the documentation that allowed values are (-1) and >=1 with the side effect of setting it to zero

Additional info:

Comment 1 melanie witt 2020-02-14 15:32:23 UTC
Here's a link to our existing documentation around the max_disk_devices_to_attach config option:

https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/15/html-single/advanced_overcloud_customization/index#sect-Config_max_disk_devices_to_attach

Comment 13 errata-xmlrpc 2022-09-21 12:09:13 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Release of components for Red Hat OpenStack Platform 17.0 (Wallaby)), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2022:6543