the maximum bitrate for blu-ray is 40mbps [not mBps]. that's 5MB/second.
5MB/second = 300MB/minute = 18GB/hour.
12PB [or 12,000TB - remember 1TB = 1024GB before formatting] / 18GB is a satanic 666,666 hours of completely uncompressed 1080p.
[or if James Cameron has his way, 12PB will store about 2,500 hours of 60fps quad HD 3D Avatar nonsense].
here's an idea of where video bitrates are heading: http://bit.ly/goBzat
blu-ray is a highly compressed format. 5MB/s is highly compressed compared to uncompressed 1080p 24fps, which is 95MB/s for 8-bit color and 127MB/s for 10-bit color. This is 334 or 445GB/hr. Yeah Blu-ray is pretty damn compressed.