Xu, the datanode only stores the amount of data provided. If the last block only has, e.g., 10 bytes in it, then the datanode will use one low-level block (the minimum space allocation from the underlying file system) to store those 10 bytes. Typically, low-level blocks are 8KB, but that depends on the server's OS and FS configuration -- it's not visible to Hadoop. It definitely won't use up 64MB of datanode storage.
--Matt On May 5, 2011, at 12:49 AM, cheng xu wrote: Hi all. as we know. the last block of file may be less then 64MB(as default configged), then what will hdfs do with the remained space in the block?? left for other files or just left unused?? any answer or related url is appreciated! thanks xu
