Redundancy occurs when parallel database systems keep copies of each data item (or division) on many nodes. Explain why it is preferable to spread copies of data items assigned to a node among many...

Redundancy occurs when parallel database systems keep copies of each data item (or division) on many nodes.
Explain why it is preferable to spread copies of data items assigned to a node among many other nodes rather than keeping all copies in the same node. (or a group of nodes)
Section B discusses in depth the advantages and disadvantages of employing RAID storage as opposed to keeping an additional duplicate of each data item. b.