Bug 1498213

Summary:	Increase ARP cache size on loadbalancers
Product:	OpenShift Container Platform	Reporter:	Jiří Mencák <jmencak>
Component:	Installer	Assignee:	Jiří Mencák <jmencak>
Status:	CLOSED ERRATA	QA Contact:	Johnny Liu <jialiu>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	3.7.0	CC:	aos-bugs, jeder, jokerman, mmccomas
Target Milestone:	---	Keywords:	NeedsTestCase
Target Release:	3.7.0
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	aos-scalability-37
Fixed In Version:		Doc Type:	Known Issue
Doc Text:	This is a known issue as openshift tuned profiles were never set on RHEL Atomic Host, only RHEL.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2017-11-28 22:14:33 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 Jiří Mencák 2017-10-03 18:21:16 UTC

Description of problem:
On RHEL Atomic Host the ARP garbage collection thresholds are too low causing problems with OCP HA deployments with 1k+ nodes.

Version-Release number of selected component (if applicable):
All

How reproducible:
Always

Steps to Reproduce:
1. Install RHEL Atomic Host OCP HA cluster with a loadbalancer and query sysctl values for net.ipv[46].neigh.default.gc_thresh[1-3]

Actual results:
net.ipv4.neigh.default.gc_thresh1 = 128
net.ipv4.neigh.default.gc_thresh2 = 512
net.ipv4.neigh.default.gc_thresh3 = 1024
net.ipv6.neigh.default.gc_thresh1 = 128
net.ipv6.neigh.default.gc_thresh2 = 512
net.ipv6.neigh.default.gc_thresh3 = 1024

Expected results:
net.ipv4.neigh.default.gc_thresh1 = 8192
net.ipv4.neigh.default.gc_thresh2 = 32768
net.ipv4.neigh.default.gc_thresh3 = 65536
net.ipv6.neigh.default.gc_thresh1 = 8192
net.ipv6.neigh.default.gc_thresh2 = 32768
net.ipv6.neigh.default.gc_thresh3 = 65536

Additional info:
https://github.com/openshift/openshift-ansible/pull/5645

Comment 1 Johnny Liu 2017-10-13 05:41:43 UTC

Verified this bug with openshift-ansible-3.7.0-0.148.0.git.0.b35eb14.el7.noarch, and PASS.

After installation, go to check:
on LB host:
# sysctl -a |grep "neigh.default.gc_thresh"
net.ipv4.neigh.default.gc_thresh1 = 8192
net.ipv4.neigh.default.gc_thresh2 = 32768
net.ipv4.neigh.default.gc_thresh3 = 65536
net.ipv6.neigh.default.gc_thresh1 = 8192
net.ipv6.neigh.default.gc_thresh2 = 32768
net.ipv6.neigh.default.gc_thresh3 = 65536


On node host:
#  sysctl -a |grep "neigh.default.gc_thresh"
net.ipv4.neigh.default.gc_thresh1 = 8192
net.ipv4.neigh.default.gc_thresh2 = 32768
net.ipv4.neigh.default.gc_thresh3 = 65536
net.ipv6.neigh.default.gc_thresh1 = 8192
net.ipv6.neigh.default.gc_thresh2 = 32768
net.ipv6.neigh.default.gc_thresh3 = 65536

Comment 4 errata-xmlrpc 2017-11-28 22:14:33 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, 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/RHSA-2017:3188