What happens when we delete a file in HDFS?

Actually any file stored in hdfs is split in blocks (chunks of data) and each block is replicated 3 times by default. When you delete a file you remove the metadata pointing to the blocks that is stored in Namenode. Blocks are deleted when there is no reference to them in the Namenode metadata.

Can the files in HDFS can be deleted?

Remove a file from HDFS, similar to Unix rm command. For recursive delete, use command -rm -r .

What happened if we delete any file from HDFS all the replicas associated with deleted file will be deleted or not?

To answer your query, deleting a file doesn’t delete the file contents and its blocks from the datanodes.

How delete all data from HDFS?

hdfs rm -r will delete the path you have provided recursively. The specified location will be deleted from hdfs cluster. So, that means it is deleted from entire hdfs cluster. If trash option is enabled, it will move the deleted files to trash directory.

How do I delete old files in HDFS?

Delete files older than 10days on HDFS

1. There is no find command, but hdfs dfs -ls -R /path/to/directory | egrep .
2. @cricket_007 but how do we do the older than ‘x’ days?
3. You’d have to cut out the date portion of the standard output, store that filtered file list, and run hdfs dfs -rm in a loop…
4. I use this script.

What command would you use to delete the file from HDFS?

You will find rm command in your Hadoop fs command. This command is similar to the Linux rm command, and it is used for removing a file from the HDFS file system. The command –rmr can be used to delete files recursively.

What happens when a data node fails while during processing?

If a DataNode fails to heartbeat for reasons other than disk failure, it needs to be recommissioned to be added back to the cluster. If a DataNode rejoins the cluster, there is a possibility for surplus replicas of blocks that were on that DataNode.

What happens if one of the DataNodes gets failed in HDFS?

What happens if one of the Datanodes gets failed in HDFS? Namenode periodically receives a heartbeat and a Block report from each Datanode in the cluster. Every Datanode sends heartbeat message after every 3 seconds to Namenode.

What happened if we delete any file from HDFS all the replicas associated with deleted file will be deleted or not if present in HDFS then why and no then why?

When a file in HDFS is deleted by a user *?

4) When a file in HDFS is deleted by a user B.It goes to trash if configured.

How to delete a file/directories from HDFS?

In order to delete a file/directories from HDFS we follow similar steps as read and write operation. For deleting a file we use – fs.delete (path, false), false indicates files are not deleted recursively, for deleting directories and files recursively pass true instead of false.

How do I delete all files in a Hadoop folder?

Use hdfs command to delete all files in it. For example, if your hadoop path is /user/your_user_name/* then use asterisk to delete all files inside the specific folder. hdfs dfs -rm -r /user/your_user_name/*

What is HDFS in Hadoop?

HDFS (Hadoop file system) is most commonly used storage entity in hadoop ecosystem. Read and write operation is very common when we deal with HDFS. Along with file system commands we have file system API to deal with read/write/delete operation programmatically.

How to read a file from HDFS?

In order to read a file from HDFS, create a Configuration object followed by a FileSystem object by passing configuration object in it. Add core-site.xml as resource to configuration object.