In the data backup application scenario, which of the following descriptions about the quality of the optical disc storage medium is wrong?

• A.Applicable to scenarios that require high backup capacity.
• B.Data can be stored for a long time.
• C.It is suitable for scenarios that do not require high backup speed.
• D.It is suitable for backup scenarios that do not need to be frequently erased.

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A company wants to deploy a big data platform. It is estimated that the number of files in the entire cluster can reach trillions, and the number of files in a single NameNode exceeds 100 million. The use of the native HDFS MameNode master/standby mode can meet the demand.

• A.True
• B.False

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Compared with traditional RAID algorithms, the erasure code redundancy technology provides higher reliability and more flexible redundancy policies.
Which of the following statements about the working principle of erasure code is false?

• A.N+M data blocks are concurrently stored to different nodes.
• B.In erasure code storage mode, a concurrent failure of M-1 disks is tolerated at most.
• C.Data to be written is divided into N data blocks of the same size.
• D.The erasure code algorithm calculates M parity blocks for every N consecutive data blocks. (The value of N is smaller than that of M.)

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Which of the following descriptions is correct?

• A.Backup schemes are usually implemented using snapshot, mirroring or replication technology.
• B.The goal of backup is to prevent human mis-operation or system problems. It saves historical data and the recovery time is relatively long.

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Regarding target deduplication, which of the following description is incorrect?

• A.Does not occupy the resources of the source.
• B.The data block is transferred from the source end to the target end, and the deduplication operation is performed on the target end.
• C.Cannot save transmission bandwidth.
• D.Target end deduplication is equivalent to post-processing deduplication (Post-procesig).

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