HDFS is a filesystem designed for storing huge amount of data. The following are the features of HDFS.
Support very large files: this is the major feature of HDFS. Hadoop clusters that are running today are able to store huge amount of data even Petabytes and Zetabytes.
Commodity Hardware: HDFS require only commodity hardware. Commodity hardware in the sense, the hardware which is available for most of the vendors. This does not need high configured hardware.
Multiple Writers, arbitrary file modifications: Once if the file is stored on top of HDFS cluster, we cannot write the data on that file. In HDFS multiple writers are not encouraged. If we want to do so, you must delete the file on HDFS, update it in local file system and then again place it in HDFS cluster.Hadoop is a Write once - Read many times mechanism.
High Latency: Latency means, the amount of time taken to fetch the data. High latency in HDFS might be because it contains more number of nodes(1000+ for some huge amount of data). Suppose, if we consider RDBMS, when we pose the query we may get the data in 0.01 seconds, but in hadoop it may take 0.11 seconds. This High latency is one of the limitation of Hadoop.
Streaming data access(Sequential flow of data access): Suppose if we want to access the data from the 1500th line, we need to process the data from line one to 1500 unnecessarily. In hadoop we cannot access the data Randomly. This is another drawback of Hadoop. To overcome this HBASE is introduced.
