名称节点处于安全模式 [英] Name node is in safe mode

问题描述

我提到这些问题

如何解决这个问题？

解决方案

这是否总是发生或者仅在开始时才启动hadoop？

如果只是在开始的时候，然后等待一段时间，以便NameNo在访问hdfs之前检查一切是否正常。如果它在相当长的时间后没有离开安全模式，那意味着文件系统存在一些不平衡（例如在复制或损坏的块下）。在一段时间后，复制块将自动保持平衡。对于损坏的块，您可以查看此命令的输出：

hdfs fsck -list-corruptfileblocks

尝试使用以下命令删除损坏的块：

hdfs fsck / -delete code



如果@Nishu建议不起作用，请使用 hdfs dfsadmin -safemode leave 命令强制使NameNode超出安全模式。一旦你这样做了，检查 hdfs dfsadmin -safemode get 的输出以确认safemode实际上是关闭的。

I referred to these questions Name node is in safe mode. Not able to leave and SafeModeException : Name node is in safe mode.

the commands i have executed is below

it shows that the safe mode is off but the immediate next command shows name node is in safe mode.

and ls /root is shown below

how to fix it ??

解决方案

Does this happen always Or only at the beginning only when you start hadoop?

If only at the beginning, then wait for sometime in order for NameNode to check if everything is okay before you access hdfs. If it's not leaving safemode after a considerable amount of time, that means there is some imbalance in the filesystem (e.g. under replicated or corrupted blocks). Under replicated blocks will be automatically balanced after some time. For corrupted blocks, you can have a look at output of this command:

hdfs fsck -list-corruptfileblocks

And try to delete corrupted blocks using:

hdfs fsck / -delete

If this does not help, as suggested by @Nishu, use hdfs dfsadmin -safemode leave command to get NameNode out of safemode forcefully. Once you do so, check the output of hdfs dfsadmin -safemode get to confirm that safemode is actually turned off.

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