The drive's capacity shows only 8.4GB, but should be 9.1GB!

This is a common problem when using a binary based number (computers, Operating Systems) to represent a decimal based number (hard drive marketing). The physical capacity of the drive is 9.1 GB based on the decimal based definition of 1 GB = 1,000,000,000 Bytes. However, the Operating System (using binary) uses the definition of 1,073,741,824 (2^30) as the definition of 1 GB. Divide 9.1 GB by 1,073,741,824 and you get 8.4 GB. Therefore, 8.4 (+/-) GB in your MAC is giving the full capacity of the drive.

Check out this link from the National Institute of Standards and Technology: http://physics.nist.gov/cuu/Units/binary.html

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