Peta Byte

With all due respect - On page 48 of the P5 notes following was the definition of a Petabyte: "The volume of big data held by large companies such as Walmart (supermarkets), Apple and EBay is measured in multiple petabytes. What’s a petabyte? It’s 1015 bytes (characters) of information. A typical disc on a personal computer (PC) holds 109 bytes (a gigabyte), so the big data depositories of these companies hold at least the data that could typically be held on 1 million PCs, perhaps even 10 to 20 million PCs." Is it right cz it should be way bigger than That.