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Bug 1563412

Summary:	FFU: nova compute reserved_host_memory_mb gets increased from 2048 to 4096 after the upgrade process
Product:	Red Hat OpenStack	Reporter:	Marius Cornea <mcornea>
Component:	documentation	Assignee:	Dan Macpherson <dmacpher>
Status:	CLOSED CURRENTRELEASE	QA Contact:	RHOS Documentation Team <rhos-docs>
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	13.0 (Queens)	CC:	augol, dbecker, dmacpher, lbezdick, lbopf, mandreou, mburns, mcornea, morazi, rhel-osp-director-maint, sathlang, srevivo
Target Milestone:	z2	Keywords:	Triaged
Target Release:	13.0 (Queens)
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Release Note
Doc Text:	The reserved host memory for OpenStack Compute (nova) has increased from 2048 MB to 4096 MB. This can affect capacity estimations for your environment. If necessary, you can reconfigure the reserved memory using the 'NovaReservedHostMemory' parameter in a environment file. For example: parameter_defaults: NovaReservedHostMemory: 2048	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-08-06 03:57:03 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:

Description Marius Cornea 2018-04-03 21:20:48 UTC

Description of problem:
FFU: nova compute reserved_host_memory_mb gets increased from 2048 to 4096 after the upgrade process:

Before upgrade:
[root@compute-0 heat-admin]# grep reserved_host_memory_mb /etc/nova/nova.conf 
reserved_host_memory_mb=2048

After upgrade:
[root@compute-0 heat-admin]# docker exec nova_compute grep reserved_host_memory_mb /etc/nova/nova.conf
#reserved_host_memory_mb=512
reserved_host_memory_mb=4096


Version-Release number of selected component (if applicable):
openstack-tripleo-heat-templates-8.0.2-0.20180327213843.f25e2d8.el7ost.noarch

How reproducible:
100%

Steps to Reproduce:
1. Deploy OSP10
2. Check reserved_host_memory_mb in /etc/nova/nova.conf 
3. Run through the FFU process
4. Check reserved_host_memory_mb in /etc/nova/nova.conf

Actual results:
The before/after values do not match.

Expected results:
This change of value may affect the initial resource capacity estimations that were taken into consideration during the OSP10 deplyoment.  

Additional info:
I'm not sure what caused this increase in requirements but in any case we should document this change so the operators are aware and can take preventive action by overriding the value pre upgrade.

Comment 2 Lukas Bezdicka 2018-04-18 15:14:01 UTC

Hi, can we make this into OSP13 documentation?

Comment 3 Dan Macpherson 2018-04-19 04:18:28 UTC

Setting release note flag for this item.

Comment 4 Lucy Bopf 2018-04-22 22:47:17 UTC

Changing requires_doc_text flag back to ? until meaningful text is added. There is currently nothing in the doc text field to pull into the Release Notes, and this results in a blank entry.

Comment 6 Marios Andreou 2018-05-16 14:58:27 UTC

just discussed on ffu call can you please check this... is it docs only and should we re-assign

Comment 7 Lukas Bezdicka 2018-05-23 14:44:23 UTC

We need to notify users that there was change to defaults.

Comment 8 Sofer Athlan-Guyot 2018-06-04 12:23:14 UTC

Hi,

do you need additional information for adding this notification into the doc ?

thanks,

Comment 9 Dan Macpherson 2018-06-04 23:42:58 UTC

Hi Sofer,

Beyond a release note letting people know about this change, is there anything else required?

- Dan

Comment 10 Sofer Athlan-Guyot 2018-06-07 10:32:18 UTC

Hey Marius,

I tend to agree with Dan that a release note could be enough here.  Would that fit the bill ?

Comment 11 Marius Cornea 2018-06-07 13:02:22 UTC

(In reply to Sofer Athlan-Guyot from comment #10)
> Hey Marius,
> 
> I tend to agree with Dan that a release note could be enough here.  Would
> that fit the bill ?

Hey Sofer,

Yes, release note works. Just to add for the info here, the nova host reserved memory can be configured via NovaReservedHostMemory parameter.

Comment 14 Dan Macpherson 2018-06-14 06:20:21 UTC

This should now appear in the GA release notes. @Marius, how does that look to you?

Comment 15 Marius Cornea 2018-06-18 14:59:44 UTC

(In reply to Dan Macpherson from comment #14)
> This should now appear in the GA release notes. @Marius, how does that look
> to you?

Looks good to me. Thanks Dan!