The metadata indicates the file mapping of the DataNode.
元数据说明DataNode的文件映射。
Each node storing data will have a datanode daemon running.
每个存储数据的节点运行一个datanode守护进程。
When the load increases in a DataNode to the threshold level, it sends a request to the NameNode.
当DataNode的负载增加到阈值级别时，它将向该NameNode发送一个请求。
Then the client flushes the block of data from the local temporary file to the specified DataNode.
客户端将本地临时文件flush到指定的 Datanode上。
Each DataNode compares its own load amount with the sum of the load amount of its nearest neighbors.
每个DataNode将自己负载量与其最近节点的负载量之和进行比较。
It also accepts operation commands and determines which DataNode should perform the action and replication.
它还接收操作命令并决定哪些DataNode应该执行操作和复制。
The jobtracker also validates requested work and, if a datanode fails for some reason, reschedules the previous task.
jobtracker还检查请求的工作，如果一个datanode由于某种原因失败，jobtracker会重新调度以前的任务。
Loads are compared by the NameNode and then the details about the free-est neighbor nodes are sent to the specific DataNode.
NameNode比较负载，然后将有关最空闲相邻节点的详细信息发送到特定的DataNode。
But, due to the characteristics of distributed storage, there are "NameNode" and "DataNode," which take each of their responsibility.
但是，由于分布式存储的性质，有“NameNode”和“DataNode”的概念，它们承担各自的责任。
Finally, each cluster will have a single jobtracker that is responsible for scheduling work at the datanodes and a tasktracker per datanode that performs the actual work.
最后，每个集群有一个jobtracker，它负责调度datanode上的工作。每个datanode有一个tasktracker，它们执行实际工作。
When a file is closed, the remaining un-flushed data in the temporary local file is transferred to the DataNode. The client then tells the NameNode that the file is closed.
当文件关闭时，在临时文件中剩余的没有flush的数据也会传输到指定的Datanode，然后客户端告诉Namenode文件已经关闭。
The jobtracker daemon requests that the datanode perform the MapReduce job, which results in a considerable amount of output (smaller here, because you're only processing two files).
jobtracker守护进程请求datanode执行MapReduce作业，这会产生相当多的输出(这里的输出比较少是因为只处理两个文件)。
The DataNode does not create all files in the same directory. Instead, it USES a heuristic to determine the optimal number of files per directory and creates subdirectories appropriately.
Datanode并不在同一个目录创建所有的文件，相反，它用启发式地方法来确定每个目录的最佳文件数目，并且在适当的时候创建子目录。
The DataNode does not create all files in the same directory. Instead, it USES a heuristic to determine the optimal number of files per directory and creates subdirectories appropriately.
Datanode并不在同一个目录创建所有的文件，相反，它用启发式地方法来确定每个目录的最佳文件数目，并且在适当的时候创建子目录。
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