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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "HadoopIsNot" by SteveLoughran
Date Tue, 11 Aug 2009 15:40:08 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

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

The comment on the change is:
fix the bullets

------------------------------------------------------------------------------
  We see a lot of emails where people hear about Hadoop, and think it will be the silver bullet
to solve all their application/datacentre problems. It is not. It solves some specific problems
for some companies and organisations, but only after they have understood the technology and
where it is appropriate. If you start using Hadoop in the belief it is a drop-in replacement
for your database or SAN filesystem, you will be disappointed.
  
  
- == Hadoop is not a substitute for a database ==
+ == Apache Hadoop is not a substitute for a database ==
  
  Databases are wonderful. Issue an SQL SELECT call against an indexed/tuned database and
the response comes back in milliseconds. Want to change that data? SQL UPDATE and the change
is in. Hadoop does not do this.
  
@@ -43, +43 @@

  
  There are some very high-end filesystems out there: GPFS, Lustre, which offer fantastic
data availability and performance, usually by requiring high end hardware (SAN and infiniband
networking, RAID storage). Hadoop HDFS cheats, delivering high local data access rates by
running code near the data, instead of being fast at shipping the data remotely. Instead of
using RAID controllers, it uses non-RAIDed storage across multiple machines.
  
- * It is not (currently) Highly Available. The Namenode is a ["SPOF"].
+  * It is not (currently) Highly Available. The Namenode is a ["SPOF"].
- * It does not (currently) offer real security. It is probably less secure than Sun's original
NFS filesystem.
+  * It does not (currently) offer real security. It is probably less secure than Sun's original
NFS filesystem.
  
  Because of these limitations, if you want a secure filesystem that is always available,
HDFS is not yet there. You can run Hadoop MapReduce over other filesystems, however.
  

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