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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "Hbase/DesignOverview" by EvgenyRyabitskiy
Date Sat, 04 Apr 2009 17:50:10 GMT
Dear Wiki user,

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The following page has been changed by EvgenyRyabitskiy:
http://wiki.apache.org/hadoop/Hbase/DesignOverview

------------------------------------------------------------------------------
  
  HBase is an [http://apache.org/ Apache] open source project whose goal is to provide Bigtable-like
storage for the Hadoop Distributed Computing Environment. HBase leverages the distributed
data storage provided by the [http://hadoop.apache.org/core/docs/current/hdfs_design.html
Hadoop Distributed File System (HDFS)] and use [http://hadoop.apache.org/zookeeper/docs/current/zookeeperOver.html
ZooKeeper] for coordination between HBase nodes.
  
- Data is logically organized into tables, rows and columns.  An iterator-like interface is
available for scanning through a row range and, of course, there is the ability to retrieve
a column value for a specific row key. Any particular column may have multiple versions for
the same row key.
+ Data is logically organized into tables, rows and columns. An iterator-like interface is
available for scanning through a row range and, of course, there is the ability to retrieve
a column value for a specific row key. Any particular column may have multiple versions for
the same row key.
  
  [[Anchor(datamodel)]]
  = Data Model =
@@ -115, +115 @@

  [[Anchor(master)]]
  == HMaster ==
  
- There is only one HMaster for a single HBase deployment.
+ There is only one HMaster for a single HBase deployment. To ensure that there is always
one active HMaster uses [http://hadoop.apache.org/zookeeper/docs/current/recipes.html#sc_leaderElection
leader election algorithm] and it's address is stored in !ZooKeaper.
  
  HMaster duties:
  
@@ -123, +123 @@

   * Assigning/unassigning regions to/from H!RegionServers (unassigning is for load balance)
   * Monitor the health of each H!RegionServer
   * Changes to the table schema and handling table administrative functions
+ 
+ == Cluster initialization ==
+ 
+ 
  
  === Assigning regions to HRegionServers ===
  

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