I don't work at Dropbox, but I do work in storage. I've seen similar systems pack ~250-500TB into a 4U box. 60 drives x 6TB drives = 360TB. Not sure how you

I don't work at Dropbox, but I do work in storage. I've seen similar systems pack ~250-500TB into a 4U box. 60 drives x 6TB drives = 360TB. Not sure how you would get anywhere over 1000TB with today's spinning drives. There is a vendor linked in Backblaze blog post (45drives) which sells 60 drive enclosures, which they somehow list at 480TB but I'm not sure how the math works out there. However, keep in mind that usable capacity is going to be less. Erasure coding has significantly less overhead than traditional raid, but there is still a cost (depends on chosen protection set). http://www.45drives.com/products/storage/xl60.php http://www.45drives.com/products/storage/xl60.php