A Related Tangent is how FB handles different photo requests by saving 4 copies with different resolutions at the time of upload. It's even worse because according to [1]:

   " The number of Haystack photos written is 12 times the number of photos uploaded since the application scales each image to 4 sizes and saves each size in 3 different locations. "

[1] https://bigdata.devcodenote.com/2015/04/haystack-facebooks-p...