Today Netflix announced that they delivered their two billionth DVD, an impressive milestone. This brought to mind something we learned in the early days of Excite, which was to never underestimate the bandwidth of physical storage media sent via UPS, the USPS or FedEx. When we opened our second datacenter circa 1996 (on the east coast in one of AOL’s datacenters) we quickly found out that it was faster, cheaper and more reliable to simply FedEx overnight an archived backup tape copy of our search index to the east coast mirror site than to transfer the files over the internet.
I’ve always thought that Netflix’s business was a brilliant bet that the bandwidth and quality of a rental experience powered by DVDs sent via USPS was going to be cheaper and exceed the capabilities of on-demand via the internet for much longer than people were expecting, and of course this turned out to be true. And now that internet tech is finally catching up to the low tech method of shipping atoms full of bits around the country, I think Netflix has done a brilliant job with their internet strategy and distribution partnerships, which should enable a graceful (and still longer-term than people expect) transition from postal delivery to internet delivery.
So when I saw the announcement of the two billionth DVD delivered, I decided to do a quick and dirty back-of-the-envelope calculation of how much data Netflix has delivered to customers in the roughly 10 years since their subscription service launched. (Apologies in advance to all the sticklers out there who might point out the imprecision of this calculation since I’m using factors of 1,000 instead of 1,024 to measure my gigabytes and petabytes.) Here goes:
A DVD has a max capacity of 4.7 gigabytes. Since Netflix also ships TV shows and the like, which don’t fill a DVD to capacity, let’s assume that the average DVD contains 4 GB of data. So, that means they’ve delivered eight billion gigabytes, or eight million terabytes, or eight thousand petabytes, which boils down to an average of 800 petabytes per year over a ten year period. Multiply that by 8 bits per byte and divide by 31,536,000 seconds per year, and you get 202,942,669,000 bits per second, or a sustained ten-year average bandwidth of 200 gigabits per second.
Of course, that’s an average spread evenly over 10 years, and today’s outgoing bandwidth from Netflix via the USPS is many times higher, given the ramp from zero DVDs shipped in the early years and given the fact that Netflix is now shipping Bluray discs, which hold 50GB vs. the 4.7GB on a traditional DVD. And, finally, given they are actually delivering movies via the net, they are now using actual net bandwidth instead of theoretically derived, USPS-enabled bandwidth, though I’m sure their actual bandwidth consumption is still dwarfed by the discs in the mail.
But still, I was surprised by the 200 Gbps number and had to check my calculations a few times to make sure I was right. And it is conceivable that that means that their theoretical bandwidth today could be in the terabit per second range. Golly.