Final answer:
The dimension of big data that deals with the amount of data, measured in petabytes or exabytes, is known as 'volume.' It represents the large scale of data collection and the challenges associated with managing and analyzing such data.
Step-by-step explanation:
The dimension of big data that refers to the sheer quantity of transactions, measured in petabytes or exabytes is known as volume. Volume captures the massive scale of data collected and stored from various sources, which today even includes data on the scale of the Library of Congress. Efficiently organizing, storing, and analyzing this voluminous data is one of the significant challenges in fields such as astronomy, where projects like the Sloan Survey have generated terabytes of data, requiring advanced computer systems and citizen science initiatives like Galaxy Zoo to process and classify such extensive datasets.
For instance, the Sloan Survey's generation of data at 8 megabytes per second, totaling over 15 terabytes throughout the project, is an example of the vast data volumes faced in modern research and data analysis. This shows the critical importance of the volume dimension when we discuss big data characteristics and the necessity for supercomputers and sophisticated algorithms for data handling.