Large-scale parallel database systems_test

[jonegoogle]

I am recently studying database and face such a question:

Large-scale parallel database systems store an extra copy of each data item on disks attached to a different processor, to avoid loss of data if one of the processors fails.
a. Instead of keeping the extra copy of data items from a processor at a single backup processor, it is a good idea to partition the copies of the data items of a processor across multiple processors. Explain why.
b. Explain how virtual-processor partitioning can be used to efficiently implement the partitioning of the copies as described above.
c. What are the benefits and drawbacks of using RAID storage instead of storing an extra copy of each data item?


I am not sure whether the lase one is the best option. I thought it is the best but still need more …