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Bug 456248 - DNS outage can cause cluster to die
Summary: DNS outage can cause cluster to die
Alias: None
Product: Red Hat Cluster Suite
Classification: Retired
Component: clumanager
Version: 3
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Lon Hohberger
QA Contact: Cluster QE
Depends On:
TreeView+ depends on / blocked
Reported: 2008-07-22 14:10 UTC by Lon Hohberger
Modified: 2018-10-19 23:42 UTC (History)
4 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2008-07-31 14:24:00 UTC

Attachments (Terms of Use)
Shortcuts DNS lookup if the IP tiebreaker is in dotted quad form (deleted)
2008-07-22 14:10 UTC, Lon Hohberger
no flags Details | Diff

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.

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