Bug 1541438

Summary:	quorum-reads option can give inconsistent reads
Product:	[Community] GlusterFS	Reporter:	Karthik U S <ksubrahm>
Component:	replicate	Assignee:	Karthik U S <ksubrahm>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	mainline	CC:	bugs, nchilaka, pkarampu, rhs-bugs, sabose, storage-qa-internal
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Clone Of:	1537480	Environment:
Last Closed:	2020-03-12 12:45:43 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Bug Blocks:	1537480

Comment 1 Karthik U S 2018-02-02 15:03:21 UTC

Description of problem:
For a file, Brick-A has pending operations on Brick-B, Brick-B has pending operations on Brick-C and Brick-C has pending operations on Brick-A. Since no two other bricks are blaming one brick any of these bricks can be considered as a good copy and a heal can be done. Reads will fail until heal happens.
The consistent read issue we found happens when Any one of the bricks go down in this state. If Brick-A goes down, Reads will be served from Brick-B and if Brick-B goes down Reads will be served from Brick-C. If Brick-C goes down reads will be served from Brick-A. All these reads could give different content.


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


How reproducible:
It is extremely difficult to hit this case. We are mostly going to simulate it by putting breakpoints in gdb.

Comment 2 Worker Ant 2018-02-02 15:06:33 UTC

REVIEW: https://review.gluster.org/19477 (cluster/afr: Implementation of generic functions for consistent read) posted (#1) for review on master by Karthik U S

Comment 3 Worker Ant 2020-03-12 12:45:43 UTC

This bug is moved to https://github.com/gluster/glusterfs/issues/941, and will be tracked there from now on. Visit GitHub issues URL for further details