Bug 1962178

Summary: [ovn] Reduce the writes to OVN SB database in metadata agent
Product: Red Hat OpenStack Reporter: Daniel Alvarez Sanchez <dalvarez>
Component: python-networking-ovnAssignee: Jakub Libosvar <jlibosva>
Status: CLOSED ERRATA QA Contact: Roman Safronov <rsafrono>
Severity: medium Docs Contact:
Priority: high    
Version: 16.1 (Train)CC: apevec, ekuris, elicohen, eolivare, ffernand, jmelvin, jraju, lhh, majopela, oblaut, rsafrono, scohen
Target Milestone: z7Keywords: Performance, Triaged
Target Release: 16.1 (Train on RHEL 8.2)   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: python-networking-ovn-7.3.1-1.20210714143305.4e24f4c.el8ost Doc Type: No Doc Update
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-12-09 20:19:32 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 Daniel Alvarez Sanchez 2021-05-19 13:03:24 UTC 
Right now, the metadata agent writes into the SB database to indicate that a network has been provisioned with metadata on a particular chassis.

This triggers updates to all clients monitoring the Chassis columns and makes neutron-server wait for an event during a VM boot up with a 15s timeouts.

On very loaded systems, it is very frequent to see the 15 seconds timeout expire so the mechanism becomes useless.

Also, on non loaded systems, the wait is not needed since cloud-init retries the metadata requests up to 20 times which exceeds by far the 15 seconds.

By eliminating this readiness mechanism we can set the grounds to make the metadata agent connect to slave instances for read-only operations.
Comment 2 Daniel Alvarez Sanchez 2021-05-19 13:05:14 UTC 
This is a scale related enhancement
Comment 10 Roman Safronov 2021-10-11 16:46:14 UTC 
Verified on RHOS-16.1-RHEL-8-20211007.n.1 with python3-networking-ovn-7.3.1-1.20210714143309.el8ost.noarch
Monitored SB DB and verified that there are no more writings to Chassis table external_ids when creating VMs. Used this command: sudo ovsdb-client monitor tcp:172.17.1.137:6642 OVN_Southbound Chassis external_ids. Before the fix there were neutron-metadata-proxy-networks parameter updates.
Comment 23 errata-xmlrpc 2021-12-09 20:19:32 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 (Red Hat OpenStack Platform 16.1.7 (Train) bug fix and enhancement 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/RHBA-2021:3762