Allow the secondary node to access objects backed up on the primary node ( this has to be done on the primary machine)

Every node has one and only one primary node type.

每个节点都有且只有一个主节点类型。

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Upon failure of the primary node the redundant node takes over.

在主节点发生故障时，冗余节点可以接管。

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There can be up to7 servers in a cluster, and any node can be the primary node.

一个集群最多可以支持7个服务器，并且任意节点都可以是主节点。

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It is understood that the lymphoma is a primary node or other lymphoid tissues of malignant tumors, is a system originated in hematopoietic malignancies, the disease can occur at any age.

据了解，淋巴癌是原发于淋巴结或其他淋巴组织的恶性肿瘤，是一种起源于造血系统的恶性肿瘤，这种病可发生于任何年龄。

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All probes will be active, but only the primary node will forward monitored transactions.

所有探测器都是活跃的，但是只有主节点会转发监视的事务。

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The increasing CPU utilization is attributed to unnecessary node hops for interrupts being taken on Ethernet adapters on non-primary nodes but being processed on CPUs on the primary node.

CPU利用率快速增加的原因是，在非主节点上的以太网适配器中接收的中断却在主节点的CPU上处理，这导致了不必要的节点跳转。

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Change the hostname of the secondary node to the primary node's hostname.

把辅助节点的主机名改为主节点的主机名。

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Once the MapReduce operation for a particular search key is completed, the NameNode returns the output value to the server and in turn to the client.

完成特定的搜索关键字MapReduce操作之后，NameNode将输出值返回到服务器并交付客户端。

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At this point, the NameNode commits the file creation operation into a persistent store.

此时Namenode才将文件创建操作提交到持久存储。

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You'll find one namenode and one secondary namenode in a Hadoop cluster.

在每个Hadoop集群中可以找到一个namenode和一个secondary namenode。

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For this reason, the NameNode can be configured to support maintaining multiple copies of the FsImage and EditLog.

因而，Namenode可以配置成支持维护多个FsImage和Editlog的拷贝。

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The NameNode uses a transaction log called the EditLog to persistently record every change that occurs to file system metadata.

对于任何对文件元数据产生修改的操作，Namenode都使用一个称为Editlog的事务日志记录下来。

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First, request the namenode to format the DFS file system.

首先，请求namenode对DFS文件系统进行格式化。

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The existence of a single NameNode in a cluster greatly simplifies the architecture of the system.

单一节点的Namenode大大简化了系统的架构。

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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。

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You can perform a couple of tests to ensure that Hadoop is up and running normally ( at least the namenode).

可以通过几个检查确认Hadoop（至少是namenode）已经启动并正常运行。

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They also respond to commands that create, delete, and replicate blocks received from the NameNode.

它们还响应从NameNode接收的块创建、删除和复制命令。

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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。

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Recall that at the top of the Hadoop cluster is the namenode, which manages the HDFS.

位于Hadoop集群最上层的是namenode，它管理HDFS。

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The NameNode executes file system namespace operations like opening, closing, and renaming files and directories.

Namenode执行文件系统的namespace操作，例如打开、关闭、重命名文件和目录，同时决定block到具体Datanode节点的映射。

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