MCQs on Advanced HDFS Commands | Hadoop HDFS
Master Advanced HDFS Commands for efficient management of distributed systems. Explore fsck for health checks, advanced file operations, handling DataNode failures, and managing permissions and ownership directly through the command line interface (CLI).
1. Using fsck Command to Check HDFS Health
- What is the purpose of the
hdfs fsckcommand?- A) To check DataNode configurations
- B) To perform HDFS health checks
- C) To replicate blocks
- D) To delete corrupted files
- Which option with
fsckdisplays detailed block information?- A)
-move - B)
-files - C)
-blocks - D)
-replication
- A)
- What does the
hdfs fsckcommand report?- A) Metadata and user access details
- B) File system status and block health
- C) NameNode uptime
- D) DataNode performance
- How can you use
fsckto fix under-replicated blocks?- A) By running
hdfs fsck -fix - B) By restarting NameNode
- C) By enabling dynamic replication
- D) By increasing the replication factor manually
- A) By running
- What does the
CORRUPTstatus infsckoutput indicate?- A) Replication is too high
- B) Block files are missing or inaccessible
- C) DataNode is overloaded
- D) File permissions are incorrect
- How do you exclude non-critical errors in the
fsckreport?- A) Use
-ignore - B) Use
-status - C) Use
-locations - D) Use
-show
- A) Use
2. Advanced HDFS File Management
- Which command moves a file within HDFS?
- A)
hdfs dfs -moveToLocal - B)
hdfs dfs -mv - C)
hdfs dfs -cp - D)
hdfs dfs -rm
- A)
- What does
hdfs dfs -copyToLocaldo?- A) Copies files from HDFS to the local filesystem
- B) Copies files between HDFS directories
- C) Moves files from HDFS to local storage
- D) Creates backup copies in HDFS
- How can you upload files from the local system to HDFS?
- A)
hdfs dfs -moveFromLocal - B)
hdfs dfs -put - C)
hdfs dfs -copyToLocal - D)
hdfs dfs -fetch
- A)
- Which command is used to rename a file in HDFS?
- A)
hdfs dfs -rename - B)
hdfs dfs -mv - C)
hdfs dfs -cp - D)
hdfs dfs -edit
- A)
- What is the difference between
-putand-copyFromLocal?- A)
-putrequires HDFS privileges,-copyFromLocaldoes not - B)
-putoverwrites by default,-copyFromLocaldoes not - C) Both commands are identical
- D)
-putis faster than-copyFromLocal
- A)
- How do you recursively copy a directory in HDFS?
- A)
hdfs dfs -copyDir - B)
hdfs dfs -cp - C)
hdfs dfs -cp -r - D)
hdfs dfs -recursive
- A)
- What happens when you run
hdfs dfs -rmron a directory?- A) Deletes only the specified files
- B) Deletes the directory recursively
- C) Archives the directory
- D) Deletes directory metadata
- Which option allows you to append data to an existing HDFS file?
- A)
-appendToFile - B)
-addToFile - C)
-editFile - D)
-extendFile
- A)
- How do you view the contents of an HDFS file without downloading it?
- A)
hdfs dfs -read - B)
hdfs dfs -cat - C)
hdfs dfs -head - D)
hdfs dfs -open
- A)
3. DataNode Failures and Recovery Procedures
- What happens to data stored on a failed DataNode?
- A) It is automatically deleted
- B) It is replicated to other nodes
- C) It becomes inaccessible permanently
- D) It is moved to a backup directory
- Which HDFS process ensures data availability during DataNode failures?
- A) Automatic failover
- B) DataNode rebalancing
- C) Block replication
- D) SecondaryNameNode synchronization
- How can you manually decommission a DataNode?
- A) By updating the
hdfs-site.xmlfile - B) By restarting the NameNode
- C) By disabling dynamic replication
- D) By stopping the SecondaryNameNode
- A) By updating the
- What command is used to check the status of DataNodes?
- A)
hdfs dfsadmin -report - B)
hdfs dfs -ls - C)
hdfs fsck -nodes - D)
hdfs admin -datanode
- A)
- How does HDFS handle a full DataNode disk?
- A) DataNode is shut down
- B) Blocks are moved to other nodes
- C) Replication factor is increased
- D) Data is deleted from the node
- What is the first step in recovering a failed DataNode?
- A) Restart the NameNode
- B) Restart the DataNode service
- C) Delete corrupted blocks
- D) Decrease replication factor
- What does HDFS safe mode enable during failure recovery?
- A) Enables block edits
- B) Disables write operations temporarily
- C) Enables data movement
- D) Resets DataNode logs
4. Managing Permissions and Ownership via CLI
- Which command changes the ownership of an HDFS file?
- A)
hdfs dfs -setOwner - B)
hdfs dfs -chown - C)
hdfs dfs -perm - D)
hdfs dfs -own
- A)
- How do you modify the permissions of an HDFS file?
- A)
hdfs dfs -chmod - B)
hdfs dfs -setPerm - C)
hdfs dfs -chperm - D)
hdfs dfs -modPerm
- A)
- What does the
rwxformat in HDFS file permissions mean?- A) Read, write, execute
- B) Replication, write, execute
- C) Read, write, delete
- D) Read, write, copy
- Which user can modify all files in HDFS?
- A) The DataNode admin
- B) The HDFS superuser
- C) The NameNode user
- D) Any authorized user
- What does the command
hdfs dfs -ls -Rdo?- A) Lists all files recursively
- B) Displays file ownerships only
- C) Shows hidden files in HDFS
- D) Lists files sorted by replication
- How do you ensure only specific users can access a file in HDFS?
- A) By changing file ownership
- B) By setting appropriate permissions
- C) By moving the file to a private directory
- D) By encrypting the file
- What does the sticky bit in HDFS permissions allow?
- A) Only the file owner can delete or modify files in a directory
- B) Files are replicated to specific nodes
- C) Blocks are never moved between nodes
- D) Files are locked for all users
- How do you verify HDFS file ownership?
- A)
hdfs dfs -checkOwner - B)
hdfs dfs -ls - C)
hdfs dfs -viewOwner - D)
hdfs dfs -stat
- A)
Answers
| Qno | Answer |
|---|---|
| 1 | B) To perform HDFS health checks |
| 2 | C) -blocks |
| 3 | B) File system status and block health |
| 4 | A) By running hdfs fsck -fix |
| 5 | B) Block files are missing or inaccessible |
| 6 | A) Use -ignore |
| 7 | B) hdfs dfs -mv |
| 8 | A) Copies files from HDFS to the local filesystem |
| 9 | B) hdfs dfs -put |
| 10 | B) hdfs dfs -mv |
| 11 | B) -put overwrites by default, -copyFromLocal does not |
| 12 | C) hdfs dfs -cp -r |
| 13 | B) Deletes the directory recursively |
| 14 | A) -appendToFile |
| 15 | B) hdfs dfs -cat |
| 16 | B) It is replicated to other nodes |
| 17 | C) Block replication |
| 18 | A) By updating the hdfs-site.xml file |
| 19 | A) hdfs dfsadmin -report |
| 20 | B) Blocks are moved to other nodes |
| 21 | B) Restart the DataNode service |
| 22 | B) Disables write operations temporarily |
| 23 | B) hdfs dfs -chown |
| 24 | A) hdfs dfs -chmod |
| 25 | A) Read, write, execute |
| 26 | B) The HDFS superuser |
| 27 | A) Lists all files recursively |
| 28 | B) By setting appropriate permissions |
| 29 | A) Only the file owner can delete or modify files in a directory |
| 30 | B) hdfs dfs -ls |