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The following page has been changed by SteveLoughran:
http://wiki.apache.org/hadoop/SPOF

The comment on the change is:
explain SPOF. 

New page:
= SPOF: Single Point of Failure =

An SPOF is a single part of a system, which, if it fails, takes down the entire 
system. 

In Hadoop, the NameNode is a SPOF. DNS may also be SPOF, unless you have 
failover. The network may be a SPOF, depending on is redundancy, as can be the 
room's power supply. 

People can be SPOFs too. If only one person knows the database admin password, 
you can be sure they are on vacation when the password is needed. If only one 
developer understands how the mission-critical MapReduce algorithm works, they 
are the SPOF. 


There is always a SPOF. Even when you think you have anticipated and eliminated 
every SPOF, there is one out there, waiting. How you find it? You wait.

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