There are bugs but it is normal life !

Hadoop is evolving very fast and sometimes you can find bugs. Be sure to check for your version / component what are the bugs :

• Hive JIRA
• Hadoop JIRA
• Pig JIRA
• Spark JIRA
• HBase JIRA

Hadoop 2.0 !

Apache Hadoop 2.0 has just been released some days ago ! Hadoop is no longer only a MapReduce container but a multi data-framework container and provides High Availability, HDFS Federation, NFS and snapshot !

Flume daemons !

• Source (consumes events delivered to it by an external source)
• Channel (stores temporarily event's data and help to provide end-to-end reliability of the flow)
• Sink (removes the event from the channel and transfer/write it)

Both of them run asynchronously with the events staged in the channel.

Real time Hadoop !

Want to use Hadoop for real time processing ? Then use Flume for collecting, Storm for calculation and HBase for handling client IO !