Bug 1759875 - afr: support split-brain CLI for replica 3
Summary: afr: support split-brain CLI for replica 3
Keywords:
Status: POST
Alias: None
Product: Red Hat Gluster Storage
Classification: Red Hat
Component: replicate
Version: rhgs-3.5
Hardware: Unspecified
OS: Unspecified
unspecified
high
Target Milestone: ---
: ---
Assignee: Ravishankar N
QA Contact: nchilaka
URL:
Whiteboard:
Depends On: 1756938 1760791 1760792
Blocks:
TreeView+ depends on / blocked
 
Reported: 2019-10-09 10:02 UTC by Ravishankar N
Modified: 2020-01-10 17:47 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of: 1756938
Environment:
Last Closed:
Target Upstream Version:


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Description Ravishankar N 2019-10-09 10:02:57 UTC
+++ This bug was initially created as a clone of Bug #1756938 +++

Description of problem:

http://post-office.corp.redhat.com/archives/gluster-tech-list/2019-September/msg00137.html

I want to propose this for rhgs-3.5.1 as it can be really valuable for GSS to be able to use the existing CLI commands to fix corner split-brain cases even in replica 3.

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Ever since we added quorum checks for lookups in afr via commit
bd44d59741bb8c0f5d7a62c5b1094179dd0ce8a4, the split-brain resolution
commands would not work for replica 3 because there would be no
readables for the lookup fop.

The argument was that split-brains do not occur in replica 3 but we do
see (data/metadata) split-brain cases once in a while which indicate that  there are   a few bugs/corner cases yet to be discovered and fixed.

Fortunately, commit  8016d51a3bbd410b0b927ed66be50a09574b7982 added
GF_CLIENT_PID_GLFS_HEALD as the pid for all fops made by glfsheal. If we
leverage this and allow lookups when pid is GF_CLIENT_PID_GLFS_HEALD,
split-brain resolution commands will work for replica 3 volumes too.

Attempting a patch which does this.

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