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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
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2008-07-31 14:24:00 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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.