BD

https://en.wikipedia.org/wiki/Big_data BD 

https://en.wikipedia.org/wiki/Blu-ray vs. DVD

https://www.ibm.com/big-data/us/en ,

https://www.sas.com/en_us/insights/big-data/what-is-big-data.html ,

http://www.cmswire.com/cms/information-management/breaking-down-big-data-the-value-in-metadata-026985.php ,

http://www.datasciencecentral.com/profiles/blogs/why-you-need-metadata-for-big-data-success