Bug 1380318 - pcs gives a false positive quorum error upon removing a node
Summary: pcs gives a false positive quorum error upon removing a node
Keywords:
Status: CLOSED WORKSFORME
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: pcs
Version: 7.3
Hardware: x86_64
OS: Linux
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Tomas Jelinek
QA Contact: cluster-qe@redhat.com
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-09-29 09:43 UTC by Roman Bednář
Modified: 2016-10-18 10:33 UTC (History)
5 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
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Clone Of:
Environment:
Last Closed: 2016-10-18 10:33:03 UTC
Target Upstream Version:


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Description Roman Bednář 2016-09-29 09:43:08 UTC
pcs warns user about losing a quorum upon node removal even though it's not true.
In scenario shown below we have a 4 node cluster setup with qdevice, removing a node results in vote recalculation and quorum is not lost.

Tested with: pcs-0.9.152-10.el7.x86_64


# pcs status
Cluster name: STSRHTS28875
Stack: corosync
Current DC: virt-281 (version 1.1.15-11.el7-e174ec8) - partition with quorum
Last updated: Thu Sep 29 11:26:46 2016		Last change: Thu Sep 29 11:26:05 2016 by hacluster via crmd on virt-281

4 nodes and 12 resources configured

Online: [ virt-279 virt-280 virt-281 virt-282 ]

Full list of resources:

 fence-virt-279	(stonith:fence_xvm):	Started virt-280
 fence-virt-280	(stonith:fence_xvm):	Started virt-281
 fence-virt-281	(stonith:fence_xvm):	Started virt-282
 fence-virt-282	(stonith:fence_xvm):	Started virt-279
 Clone Set: dlm-clone [dlm]
     Started: [ virt-279 virt-280 virt-281 virt-282 ]
 Clone Set: clvmd-clone [clvmd]
     Started: [ virt-279 virt-280 virt-281 virt-282 ]

Daemon Status:
  corosync: active/enabled
  pacemaker: active/enabled
  pcsd: active/enabled

# pcs quorum status 
Quorum information
------------------
Date:             Thu Sep 29 11:26:51 2016
Quorum provider:  corosync_votequorum
Nodes:            4
Node ID:          2
Ring ID:          1/160
Quorate:          Yes

Votequorum information
----------------------
Expected votes:   7
Highest expected: 7
Total votes:      7
Quorum:           4  
Flags:            Quorate Qdevice 

Membership information
----------------------
    Nodeid      Votes    Qdevice Name
         1          1   A,NV,NMW virt-279
         2          1    A,V,NMW virt-280 (local)
         3          1    A,V,NMW virt-281
         4          1    A,V,NMW virt-282
         0          3            Qdevice


>False positive message when trying to remove node:
# pcs cluster node remove virt-279
Error: Removing the node will cause a loss of the quorum, use --force to override

# pcs cluster node remove virt-279 --force
virt-279: Stopping Cluster (pacemaker)...
virt-279: Successfully destroyed cluster
virt-280: Corosync updated
virt-281: Corosync updated
virt-282: Corosync updated

# pcs status
Cluster name: STSRHTS28875
Stack: corosync
Current DC: virt-281 (version 1.1.15-11.el7-e174ec8) - partition with quorum
Last updated: Thu Sep 29 11:27:34 2016		Last change: Thu Sep 29 11:27:24 2016 by root via crm_node on virt-280

3 nodes and 10 resources configured

Online: [ virt-280 virt-281 virt-282 ]

Full list of resources:

 fence-virt-279	(stonith:fence_xvm):	Started virt-280
 fence-virt-280	(stonith:fence_xvm):	Started virt-281
 fence-virt-281	(stonith:fence_xvm):	Started virt-282
 fence-virt-282	(stonith:fence_xvm):	Started virt-280
 Clone Set: dlm-clone [dlm]
     Started: [ virt-280 virt-281 virt-282 ]
 Clone Set: clvmd-clone [clvmd]
     Started: [ virt-280 virt-281 virt-282 ]

Daemon Status:
  corosync: active/enabled
  pacemaker: active/enabled
  pcsd: active/enabled

# pcs quorum status 
Quorum information
------------------
Date:             Thu Sep 29 11:27:36 2016
Quorum provider:  corosync_votequorum
Nodes:            3
Node ID:          2
Ring ID:          2/164
Quorate:          Yes

Votequorum information
----------------------
Expected votes:   5
Highest expected: 5
Total votes:      5
Quorum:           3  
Flags:            Quorate Qdevice 

Membership information
----------------------
    Nodeid      Votes    Qdevice Name
         2          1    A,V,NMW virt-280 (local)
         3          1    A,V,NMW virt-281
         4          1    A,V,NMW virt-282
         0          2            Qdevice

Comment 4 Tomas Jelinek 2016-10-18 10:33:03 UTC
I am not able to reproduce this. Based on discussion with the reporter I am closing this as works for me.


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