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Comment by Cthulhu_ | Hacker News Reader

Let's take the US. 317 million people, assuming they call for an average of 10 minutes (based on nothing whatsoever, btw), gives approx. (10317) / 60 = 53 million hours of phone conversations a day.

Given 916.259 hours = 3 TB, 53M / 916.259 = 57 3 TB = 172 TB of data /a day/. And that's just the US. Even if you adjust the average to just one minute a day, you're still looking at 17 TB / day, which should be sorta manageable I reckon.

But it's not just the US. Let's assume they want to track all voice communications globally, rounding it to an even 7 billion, ten minutes a day. I'm counting 3819 TB/day. That's a lotta 3 TB hard drives.

tl;dr: big data is big. disclaimer: I suck at basic arithmetic, I probably made a miscalculation.

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~200TB/day is entirely within the room the NSA's budget allows.

You don't need to record all phones in the world if you have the metadata of all calls in the world. The NSA or another spy agency could record only calls that match a given pattern: place from which the call originates, who is being called, time of call, previous calls made or received by the line, when the line or phone was purchased, whether this phone's call patterns resemble another phone's call patterns, etc.

They wouldn't achieve 100% coverage, but efficacy would probably be 99%+.

I would guess the problem with this kind of semi-targeted collection is processing power to decide who is a target and schedule the line taps.

Or, record all of it that you can into a daily or weekly cache, and then keep in indefinite (expensive) storage the things which are Statistically Interesting but outside our current budget/capabilities to store forever.

Yes, good point. You don't have to store everything forever, you can have tiers of interestingness — capture everything, read it looking for certain patterns, store anything that matches those patterns forever, store stuff that matches [secondary, less important but still useful pattern] for a few years, and store all other calls for a few months or a year.

Phone calls are quite low quality audio, but I don't expect the NSA to be limited to consumer grade text-to-speech technology, so at least for calls in some languages, they could store the transcripts forever.

EDIT: Apart from processing power, another expensive problem with such a setup is memory to store the firehose temporarily.

EDIT 2: If you were wondering, 200TB/day would run at $7500 for 50 4TB external hard drives at $150 each, assuming you wanted to use a Backblaze-like setup. In a year, that's $2.7 million. (This doesn't account for redundancy.)

I think they can handle it in Utah:

"An article by Forbes estimates the storage capacity as between 3 and 12 exabytes in the near term" [1]

[1] https://en.wikipedia.org/wiki/Utah_Data_Center

Which gives you between 2-10 years of storage if it was recording everyone in the world. (Based on the assumptions above).

I think you need to divide that by 2 since conversations happen in pairs, and most people in the US are talking to someone else in the US.

You rate 17 TB / day as "sorta manageable I reckon" for the federal goverment? Your local Best Buy could meet that demand.

I estimate an upper bound on the cost to be about $11 million/year:

https://docs.google.com/spreadsheet/ccc?key=0AqWtA_3af-R0dE5...

Well, for starters, if most calls are internal to the US, half of those ten minutes will be shared with another phone (unless you're just counting outgoing calls, not ingoing calls, for the "magic" 10 minute number). So if you're talking average talk time, you need to divide by two. The effect of conference calls is probably(?) negligible however.

Now, lets take a number, say 4PB/day, or 120 PB/month, say that we put each call to S3, and that each call lasts 2 minutes (on average), so 5x317x30x10^6~ 1.5 Billion puts/month, and lets say 1.5 Million gets, and a full 120PB in/out internal transfer -- that comes to just about 19M USD/Month on S3. That's certainly within NSAs budget -- and Amazon can provide that with a profit margin (assuming, they can, in fact, provide that service).

I think you made an arithmetic mistake. Look at it another way:

10 minutes per person per day * 8kbps = 600 kB per person per day. 600 kB / person / day * 365 days /year = 214 MB / year.

That's nothing. Consumer flash media is something like $0.30/GB. Let's mark that up 100x because the three letter agency doesn't care about costs and has an inefficient procurement process, so $30/GB.

0.209 GB / year * $30 / GB = $6 per person per year.

There are 300 million people in the US, but phone calls are between at least two parties, so:

300 million people * 0.5 * $6 per person per year = $900 million per year.

You can't even build a mile of highway for that little. Hell, some big cities in the US have a bigger annual deficit than that.

Count me among those who think the storage is doable. The transmission may be a bottleneck: effectively you're doubling the bandwidth requirements for phone traffic.

With local tapping and storage facilities with some mechanism for cache-and-forward including the enduring favorite: a station wagon full of tapes, or perhaps a panel-van full of flash drives, this remains within the realm of possibility.

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