Friday, 1 February 2013

INTRODUCTION OF HADOOP FILE SYSTEM

HADOOP FILE SYSTEM

         HDFS is an Apache Software Foundation project and a subproject of the Apache Hadoop project (see Resources). Hadoop is ideal for storing large amounts of data, like terabytes and petabytes, and uses HDFS as its storage system. HDFS lets you connect nodes (commodity personal computers) contained within clusters over which data files are distributed. You can then access and store the data files as one seamless file system. Access to data files is handled in a streaming manner, meaning that applications or commands are executed directly using the MapReduce processing model (again, see Resources).
hadoop file system

HDFS is fault tolerant and provides high-throughput access to large data sets. This article explores the primary features of HDFS and provides a high-level view of the HDFS architecture.
Overview of HDFS
HDFS has many similarities with other distributed file systems, but is different in several respects. One noticeable difference is HDFS's write-once-read-many model that relaxes concurrency control requirements, simplifies data coherency, and enables high-throughput access.
Another unique attribute of HDFS is the viewpoint that it is usually better to locate processing logic near the data rather than moving the data to the application space.
HDFS rigorously restricts data writing to one writer at a time. Bytes are always appended to the end of a stream, and byte streams are guaranteed to be stored in the order written.
HDFS has many goals. Here are some of the most notable:
  • Fault tolerance by detecting faults and applying quick, automatic recovery
  • Data access via MapReduce streaming
  • Simple and robust coherency model
  • Processing logic close to the data, rather than the data close to the processing logic
  • Portability across heterogeneous commodity hardware and operating systems
  • Scalability to reliably store and process large amounts of data
  • Economy by distributing data and processing across clusters of commodity personal computers
  • Efficiency by distributing data and logic to process it in parallel on nodes where data is located
  • Reliability by automatically maintaining multiple copies of data and automatically redeploying processing logic in the event of failures
So this is introduction about Haddop file system.Stay in touch for more information.
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