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Snail Mail Still Winning The Bandwidth War
LR_none writes "Today's New York Times has this short piece suggesting snail mail is the leading broadband technology, at least for video movies on demand. The article states that the 8 to 9 gigs of data on a DVD would take two weeks to download at 56kb, making Netflix' three-day distribution by mail seem speedy. (Since they can send three or more movies at once, Netflix compares favorably with DSL download speeds, too.) The author estimates Netflix alone distributes 1,500 terabytes a day, which is impressive considering the Internet carries 2,000TB a day (by estimates cited in the article). The 'immediate gratification' aspect of Internet consumerism has given a huge boost to companies like FedEx and UPS, but it's surprising to think of the post office as being the leading infrastructure provider for digital entertainment, in terms of market share and efficiency, for the forseeable future. (Disclaimer: I don't work for Netflix or the post office.)"
...never underestimate the bandwidth of a station wagon full of tapes.
if you live on the East Coast, forget about it. Mail takes 5 business days, coming and going, making Netflix not all that cheap. If you get the basic service (3 movies at a time), if you watch the movies THE DAY you get them and send them back immediately, you still can't realistically get more than say, 6 movies a month. If Netflix opened a warehouse on the East Coast, shit, I'd get the best damn service they've got. If not for that huge mail lag for us on the East Coast, their service is fucking fantastic.
To wit, from everyone's favorite echoing news site: link. They should have them in Boston, NY, and DC.
Fortran programmer...oh yeah. Array math for life!
1 gig takes 2-3 weeks over a dialup connection.
One gigabyte, divided by 5 kilobytes per second (average effective downstream rate for "56K" dial-up given line noise and TCP overhead), equals 200,000 seconds, or just under 56 hours. At that rate, an online DVD store would have already shipped the package.
CheapBytes: the fastest way for dial-up users to get an OS distro.
Will I retire or break 10K?
Actually the baud rate of a station wagon filled with backup tapes is horrible. The bandwidth however, is astounding.
I've yet to experience significant "packet loss" from Netflix, and I go through about 16 DVDs a month with their service. Since February, I've received 1 disk I couldn't read, and one disk that was broken (but I think I stepped on that one).
Packet loss is negligible.
Any sufficiently well-organized community is indistinguishable from Government.
Okay. For the rest of you who get just a little ticked off when strung along for 80 comments only to be left hanging, the bandwidth of a station wagon full of quarter-inch tapes is approximately:
:-)
13 Petabytes per second.
For comparison purposes, this is equivalent to about 650 strands of perfectly saturated, single-mode fiber optic cable.
This figure will, of course, vary depending on a number of factors. In order to compensate for your own rate of travel and storage media, simply fill in the blanks below to get your tally! It's fun for kids of all ages!
BW = (( WV / (TW * TL * TH ) ) * TC * WS / WL) , where
BW = bandwidth in bytes / second
WV = the volume of your station wagon, in cubic meters
TW = the width of each individual quarter-inch tape, in meters
TL = the length of each individual quarter-inch tape, in meters
TH = the height of each individual quarter-inch tape, in meters
TC = the capacity of each individual quarter-inch tape, in bytes
WS = the speed of your station wagon, in meters/sec
WL = the length of your station wagon, in meters
This figure assumes average instantaneous bandwidth down the length of the wagon; in reality, I would assume that the bulk of the data transfer would occur in the region nearest the trunk.
To get my figure, simply plug in: WV = 2.72, TW = 0.054, TL = 0.073, TH = 0.0105, TC = 35.0 * 10 ^ 9, WS = 26.8, WL = 4.75. These numbers are meant to describe a stuffed 2001 Subaru Outback doing 60MPH using 35GiB tapes of this form factor.
I'm told that the term 'bandwidth' applies to a communications channel. As such, a station wagon hardly counts -- it'd be like asking for the bandwidth of an IP packet. It wouldn't make sense. Similarly, it's not so much the bandwidth of the wagon as the bandwidth of the channel along which the wagon travels. With this in mind, walk with me through the following justifications.
When it's said that a SCSI bus (for example) is sustaining 20 million bits per second ( for example), what's implied is that a) if one observes the output of the bus, during every second in time, 20 million valid bits appear, on average, and b) if one observes the input of the bus, every second 20 million valid bits are being shoved onto the bus. What's not being said is how long it takes for a given bit to go from being shoved into the bus inlet to being taken out of the bus outlet. This number's usually called latency, I'm told. Regardless, in this case, the bus (channel of interest) is sustaining a bandwidth of 20 million bits per second. On average. The length of the bus is irrelevant as far as bandwidth is concerned: doubling the length of the physical bus will not change the fact that 20 million bits per second are coming out of it / going into it (at steady state), it will merely double the time it takes for a given bit to go in and then come out the other end.
So, to be proper, it should be mentioned that by 'bandwidth of a station wagon' I have computed the 'bandwidth of a one-lane road of indefinite length packed bumper-to-bumper with station wagons, each carrying quarter-inch tapes'. After all, it's the road that is really the communications channel in question, the wagon is simply the data packet.
However, if you view the communications medium as 'a road of given length with exactly one station wagon on it, carrying quarter inch tapes', then it is vital to know the length of the road in order to compute the time-averaged throughput attainable on this communications medium. Some would say that this is closer to what is assumed by the original quote. I guess it depends on your perspective. What a great way to say we're both right
Unfortunately, they seemed to have gotten rid of all their "mature" titles after they went mainstream.
Magnus.
IANAA (I am not an archeologist) but the oldest reference to such an expression on groups.google (they need a Oldest first option...) that I could find was this post wich states:
Never underestimate the bandwidth of a station wagon full of mag tapes.
-- Dennis Ritchie
The quote is attribuited to Dennis Ritchie.
coffee | nose > keyboard ©
Maybe Netflix distributes 1,500TB a day of movies, but that's using DVD's MPEG-2 compression. Encode 'em with DivX and you're gonna slash that figure by what... 80-90%?
I joined Netflix, one of the first of the DVD rental mailer companies, a long time ago and like it a lot. I was interested, then, to read a rough calculation that, in terms of 190,000 MPEG-2 format DVDs, Netflix's daily bandwidth totals 1.5 TB. This is a sizable fraction of the current total estimated Internet daily bandwidth: somewhere between 2-4 TB. Of course, Peter Wayner's calculations do not allow for the online delivery of movies in more compression-efficient formats, such as the MPEG-4-derived DIVX, where a typical 4-7 GB DVD can be reduced to around 700 MB with minimal quality loss.
I guess the CD manufacturers also thought they were safe, when a typical CD occupied 700MB of data in an era of mainly dialup connections. Then along came MP3 with its one-tenth compression ratio and so much for that idea. Netflix's current success is a temporary artifact of our restricted bandwidth and lack of suitable MPEG-4 hardware players.
And I found out from some surfing that some Netflix competitors, such as CafeDVD, QwikFlicks, and DVD Avenue, are cheaper and offer porn, something Netflix avoids.
Da Blog
You're doing the math wrong. Assuming broadcast quality video needs 5MB, a 70 channel cable system needs....5MB. A 400-channel cable system needs 5MB. Ever notice how you're never watching more than one channel at once? Maybe a little more to download guide data. But your cable line isn't 300MB.
"Moderate drinking can help prevent amputated limbs" -- Abigail Zuger, NYTimes, 12/31/02