1. The HDFS client software implements __________ checking on the contents of HDFS files.
a) metastore
b) parity
c) checksum
d) none of the mentioned
Explanation: When a client creates an HDFS file, it computes a checksum of each block of the file and stores these checksums in a separate hidden file in the same HDFS namespace.
2. Point out the correct statement.
a) The HDFS architecture is compatible with data rebalancing schemes
b) Datablocks support storing a copy of data at a particular instant of time
c) HDFS currently support snapshots
d) None of the mentioned
Explanation: A scheme might automatically move data from one DataNode to another if the free space on a DataNode falls below a certain threshold.
3. The ___________ machine is a single point of failure for an HDFS cluster.
a) DataNode
b) NameNode
c) ActionNode
d) All of the mentioned
Explanation: If the NameNode machine fails, manual intervention is necessary. Currently, automatic restart and failover of the NameNode software to another machine is not supported.
4. The ____________ and the EditLog are central data structures of HDFS.
a) DsImage
b) FsImage
c) FsImages
d) All of the mentioned
Explanation: A corruption of these files can cause the HDFS instance to be non-functional.
5. Point out the wrong statement.
a) HDFS is designed to support small files only
b) Any update to either the FsImage or EditLog causes each of the FsImages and EditLogs to get updated synchronously
c) NameNode can be configured to support maintaining multiple copies of the FsImage and EditLog
d) None of the mentioned
Explanation: HDFS is designed to support very large files.
6. __________ support storing a copy of data at a particular instant of time.
a) Data Image
b) Datanots
c) Snapshots
d) All of the mentioned
Explanation: One usage of the snapshot feature may be to roll back a corrupted HDFS instance to a previously known good point in time.
7. Automatic restart and ____________ of the NameNode software to another machine is not supported.
a) failover
b) end
c) scalability
d) all of the mentioned
Explanation: If the NameNode machine fails, manual intervention is necessary.
8. HDFS, by default, replicates each data block _____ times on different nodes and on at least ____ racks.
a) 3, 2
b) 1, 2
c) 2, 3
d) All of the mentioned
Explanation: HDFS has a simple yet robust architecture that was explicitly designed for data reliability in the face of faults and failures in disks, nodes and networks.
9. _________ stores its metadata on multiple disks that typically include a non-local file server.
a) DataNode
b) NameNode
c) ActionNode
d) None of the mentioned
Explanation: HDFS tolerates failures of storage servers (called DataNodes) and its disks.
10. The HDFS file system is temporarily unavailable whenever the HDFS ________ is down.
a) DataNode
b) NameNode
c) ActionNode
d) None of the mentioned
Explanation: When the HDFS NameNode is restarted it recovers its metadata.