Cloudera
CCA-410 · Question #53
Your cluster has 9 slave nodes. The cluster block size is set to 128 MB and it's replication factor set to three. How will the hadoop framework distribute block writes from a reducer into HDFS from…
The correct answer is C. The 9 blocks will be return randomly to the nodes; some may receive multiple blocks some may receive none. If your replication is set to 3, it will be put on 3 separate nodes. The number of nodes it's placed on is controlled by your replication factor. New blocks are placed almost randomly. There is some consideration for distribution across different racks (when hadoop is made…
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Question
Your cluster has 9 slave nodes. The cluster block size is set to 128 MB and it's replication factor set to three. How will the hadoop framework distribute block writes from a reducer into HDFS from a reducer outputting a 300MB file?
Options
- AReducer don't write blocks into HDFS
- BThe node on which the reducer is running will receive one copy of the each block. The other replicas
- CThe 9 blocks will be return randomly to the nodes; some may receive multiple blocks some may receive none
- DAll 9 nodes will each receive exactly one block
- EThe 9 blocks will be return to 3 nodes, such that each of the three get's one copy of each block
How the community answered
(47 responses)- A4% (2)
- B15% (7)
- C72% (34)
- D2% (1)
- E6% (3)
Explanation
- If your replication is set to 3, it will be put on 3 separate nodes. The number of nodes it's placed on is controlled by your replication factor. New blocks are placed almost randomly. There is some consideration for distribution across different racks (when hadoop is made aware of racks).
Topics
#HDFS block distribution#replication#DataNode#block writes
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