Bug 456248 - DNS outage can cause cluster to die
DNS outage can cause cluster to die
Product: Red Hat Cluster Suite
Classification: Red Hat
Component: clumanager (Show other bugs)
All Linux
urgent Severity urgent
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Assigned To: Lon Hohberger
Cluster QE
Depends On:
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Reported: 2008-07-22 10:10 EDT by Lon Hohberger
Modified: 2010-10-22 23:02 EDT (History)
4 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2008-07-31 10:24:00 EDT
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RHEL 7.3 requirements from Atomic Host:
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Attachments (Terms of Use)
Shortcuts DNS lookup if the IP tiebreaker is in dotted quad form (1.37 KB, patch)
2008-07-22 10:10 EDT, Lon Hohberger
no flags Details | Diff

  None (edit)
Description Lon Hohberger 2008-07-22 10:10:36 EDT
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 10:10:36 EDT
Created attachment 312347 [details]
Shortcuts DNS lookup if the IP tiebreaker is in dotted quad form
Comment 2 Lon Hohberger 2008-07-22 10:31:59 EDT
This patch does not introduce any regressions into the package.
Comment 3 Lon Hohberger 2008-07-22 10:32:15 EDT
This patch does not introduce rolling-upgrade incompatibilities.
Comment 4 Lon Hohberger 2008-07-22 12:02:27 EDT
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 10:24:00 EDT
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.

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