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Posted to common-commits@hadoop.apache.org by Apache Wiki <wi...@apache.org> on 2011/08/10 17:27:10 UTC

[Hadoop Wiki] Update of "NameNodeFailover" by SBertram

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The "NameNodeFailover" page has been changed by SBertram:
http://wiki.apache.org/hadoop/NameNodeFailover?action=diff&rev1=7&rev2=8

Comment:
Removed incorrect assertion. Adding data nodes won't affect probability of namenode hardware failure.  Statement was only true for fixed failures (e.g. "I will put an axe through one server per week")

  === Introduction ===
- As of 0.20, Hadoop does not support automatic recovery in the case of a NameNode failure.  This is a well known and recognized single point of failure in Hadoop.  The good news is that as you add more nodes to a grid, the statistical probability that the NameNode will fail goes down.
+ As of 0.20, Hadoop does not support automatic recovery in the case of a NameNode failure.  This is a well known and recognized single point of failure in Hadoop.
  
  Experience at Yahoo! shows that NameNodes are more likely to fail due to misconfiguration, network issues, and bad behavior amongst clients than actual hardware problems.  Out of fifteen grids over three year period, only three NameNode failures were related to hardware problems.