public static int getDefaultBufferSize(final FileSystem fs) {
    return fs.getConf().getInt("io.file.buffer.size", 4096);
  }
Returns the default buffer size to use during writes. The size of the buffer should probably be
a multiple of hardware page size (4096 on Intel x86), and it determines how much data is
buffered during read and write operations.
@param fs filesystem object
@return default buffer size to use during writes
hbase-common/src/main/java/org/apache/hadoop/hbase/util/CommonFSUtils.java