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This article mainly introduces the hadoop security model example analysis, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

Security Mode of HDFS

When starting a hadoop cluster, the cluster will first run in secure mode (safeMode).

So, what is the safe mode, and what does the cluster do in safe mode?

When the cluster starts, it goes into safe mode first. Security mode is a way to protect hadoop clusters. When the system is in safe mode, the integrity of the data block is checked. Assuming that the number of replicas we set (that is, the parameter dfs.replication) is 5, then there should be five replicas on dataNode, and assuming that there are only three replicas, then the ratio is 3max 50.6. A minimum copy rate of 0.999 is defined in the configuration file hdfs-default.xml, as shown in figure 7-1

Figure 7-1

Our replica rate of 0.6 is significantly less than 0.999, so the system automatically replicates to other dataNode so that the replica rate is not less than 0.999. If there are 8 copies in the system, more than 5 copies we set, then the system will also delete more than 3 copies.

Generally speaking, security mode is a protection mechanism of hadoop, which is used to ensure the security of data blocks in the cluster.

What is the impact of safe mode on us?

At this time, the client is not allowed to modify files, including uploading files, deleting files, renaming, creating folders, and so on. For example, when creating a file, there is a judgment of the security mode in the source code, as shown in figure 7-2

Figure 7-3

Normally, safe mode will run for a period of time and automatically exit. It just takes a moment for us to wait. How long to wait, we can check the remaining time of security mode exit through port 50070, as shown in figure 7-4.

Figure 7-5

Safe mode is a protection mechanism of hadoop cluster. When starting, it is best to wait for the cluster to exit automatically before performing file operations.

Thank you for reading this article carefully. I hope the article "sample Analysis of hadoop Security Mode" shared by the editor will be helpful to you. At the same time, I also hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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