Bug 456248

Summary: DNS outage can cause cluster to die
Product: [Retired] Red Hat Cluster Suite Reporter: Lon Hohberger <lhh>
Component: clumanagerAssignee: Lon Hohberger <lhh>
Status: CLOSED WONTFIX QA Contact: Cluster QE <mspqa-list>
Severity: urgent Docs Contact:
Priority: urgent    
Version: 3CC: cluster-maint, edamato, mkarg, tao
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OS: Linux   
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Last Closed: 2008-07-31 14:24:00 UTC Type: ---
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Description Flags
Shortcuts DNS lookup if the IP tiebreaker is in dotted quad form none

Description Lon Hohberger 2008-07-22 14:10:36 UTC 
Description of problem:

If a cluster member is the sole survivor in a 2-node cluster and a transient DNS
error occurs such that the cluster software can not do resolution of the IP
address, the cluster can "fail" to ping the tiebreaker.

Version-Release number of selected component (if applicable): 1.2.37-1.1

How reproducible: Rare

Steps to Reproduce:
1. Introduce transient network errors causing DNS to be unreachable
  
Actual results: cluster outage

Expected results: cluster stays up

Additional info: The cluster software MUST NEVER rely on DNS.  This behavior is
unacceptable.  The ping code does a gethostbyname() call when it should not. 
It's a simple fix.
Comment 1 Lon Hohberger 2008-07-22 14:10:36 UTC 
Created attachment 312347 [details]
Shortcuts DNS lookup if the IP tiebreaker is in dotted quad form
Comment 2 Lon Hohberger 2008-07-22 14:31:59 UTC 
This patch does not introduce any regressions into the package.
Comment 3 Lon Hohberger 2008-07-22 14:32:15 UTC 
This patch does not introduce rolling-upgrade incompatibilities.
Comment 4 Lon Hohberger 2008-07-22 16:02:27 UTC 
This bug could potentially affect any user who is running with an IP tiebreaker.
 The patch is low-impact and the work has been done.  I recommend including it.
Comment 5 Lon Hohberger 2008-07-31 14:24:00 UTC 
You can also short-circuit DNS by placing the IP tiebreaker in /etc/hosts - even
when specifying the dotted quad address instead of the hostname.

Because this workaround exists, I am not going to fix this bugzilla.