Bug 1579758

Summary:	Converting to replica 2 volume is not throwing warning
Product:	[Red Hat Storage] Red Hat Gluster Storage	Reporter:	Vijay Avuthu <vavuthu>
Component:	replicate	Assignee:	Ravishankar N <ravishankar>
Status:	CLOSED ERRATA	QA Contact:	Anees Patel <anepatel>
Severity:	high	Docs Contact:
Priority:	high
Version:	rhgs-3.4	CC:	akrishna, amukherj, apaladug, ksubrahm, rhs-bugs, sanandpa, sankarshan, sheggodu, storage-qa-internal
Target Milestone:	---	Keywords:	ZStream
Target Release:	RHGS 3.4.z Batch Update 2
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	glusterfs-3.12.2-27	Doc Type:	Release Note
Doc Text:	Previously, users were prompted with a warning message (‘replica 2 configurations can lead to split brain’) only while creating replica 2 volumes. With this update, users are now warned about the limits of replica 2 configurations when converting any other type of volume to replica 2 configuration using add-brick or remove-brick options.	Story Points:	---
Clone Of:
Clones:	1627044 (view as bug list)		Environment:
Last Closed:	2018-12-17 17:07:02 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:
Bug Depends On:	1627044
Bug Blocks:

Description Vijay Avuthu 2018-05-18 09:16:38 UTC

Description of problem:

Converting to replica 2 volume is not throwing warning

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

glusterfs-3.12.2-10.el7rhgs.x86_64

How reproducible:

Always

Below Scenarios was not throwing Warning while converting to replica 2

1) while converting distribute only to x2
2) while removing bricks from x3 to convert to x2
3) while adding/removing bricks in x2 configurations

Actual results:

Doesn't show any warning while doing above scenarios

Expected results:

Expecting to throw warning like below

" Replica 2 volumes are prone to split-brain. Use Arbiter or Replica 3 to avoid this.
Do you still want to continue?
 (y/n) y
"

Additional info:

Comment 4 Karthik U S 2018-09-11 08:35:15 UTC

Upstream patch: https://review.gluster.org/#/c/glusterfs/+/21136/

Comment 12 Anees Patel 2018-11-13 09:06:26 UTC

Verified the fix on 3.4.z Batch 2 update.
# rpm -qa | grep gluster
glusterfs-api-3.12.2-27.el7rhgs.x86_64
tendrl-gluster-integration-1.5.4-14.el7rhgs.noarch
glusterfs-client-xlators-3.12.2-27.el7rhgs.x86_64
glusterfs-events-3.12.2-27.el7rhgs.x86_64
gluster-nagios-addons-0.2.10-2.el7rhgs.x86_64
glusterfs-fuse-3.12.2-27.el7rhgs.x86_64

I am able to get the warning "Replica 2 volumes are prone to split-brain. Use Arbiter or Replica 3 to avoid this."  for the below scenarios

1) while converting distribute only to x2
2) while removing bricks from x3 to convert to x2
3) while adding/removing bricks in x2 configurations

Hence changing this to verified

Comment 13 Anees Patel 2018-11-22 17:48:27 UTC

Test-coverage is achieved by adding necessary "split-brain prone" warning check on existing remove-brick/add brick test-cases.

Comment 14 Anjana KD 2018-12-04 10:40:57 UTC

Updated the Doc text field. Kindly review for technical accuracy.

Comment 15 Karthik U S 2018-12-04 11:09:29 UTC

(In reply to Anjana from comment #14)
> Updated the Doc text field. Kindly review for technical accuracy.

LGTM.

Comment 16 errata-xmlrpc 2018-12-17 17:07:02 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/RHBA-2018:3827