Bug 211396

Summary: fencing causes loss of quorum after node removal
Product: [Retired] Red Hat Cluster Suite Reporter: Lenny Maiorani <lenny>
Component: cmanAssignee: Christine Caulfield <ccaulfie>
Status: CLOSED NOTABUG QA Contact: Cluster QE <mspqa-list>
Severity: medium Docs Contact:
Priority: medium    
Version: 4CC: cluster-maint
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Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2006-10-19 08:21:18 UTC Type: ---
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Description Lenny Maiorani 2006-10-18 21:44:47 UTC
Description of problem:
after removing a node from a 3 node cluster, fencing either of the remaining
nodes causes loss of quorum

Version-Release number of selected component (if applicable):
RHEL4 Update3

How reproducible:
always

Steps to Reproduce:
1. start with 3 node cluster, remove 1 node completely
2. instigate a fence operation on either of the remaining nodes
3. fencing causes loss of quorum
  
Actual results:
loss of quorum

Expected results:
since it is now a 2 node cluster, quorum should not be lost

Additional info:
graceful shutdown of one of the remaining nodes by stopping cman does not cause
loss of quorum

Comment 1 Christine Caulfield 2006-10-19 08:21:18 UTC
If you remove a node from a 3-node cluster you don't get a two-node cluster
unfortunately. 

What you actually have is a 3-node cluster with one node removed and quorum
artificially lowered.

The two_node cluster (as in the cluster.conf key) is a special case in cman and
requires a full cluster reboot to enable/disable the features that mean it can
continue with only a single node active.

If you need a 3 node cluster to keep running with only one active node you will
need to configure a quorum device using qdiskd.