- <title>Valutakrambod - A python and bitcoin love story</title>
- <link>http://people.skolelinux.org/pere/blog/Valutakrambod___A_python_and_bitcoin_love_story.html</link>
- <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Valutakrambod___A_python_and_bitcoin_love_story.html</guid>
- <pubDate>Sat, 29 Sep 2018 22:20:00 +0200</pubDate>
- <description><p>It would come as no surprise to anyone that I am interested in
-bitcoins and virtual currencies. I've been keeping an eye on virtual
-currencies for many years, and it is part of the reason a few months
-ago, I started writing a python library for collecting currency
-exchange rates and trade on virtual currency exchanges. I decided to
-name the end result valutakrambod, which perhaps can be translated to
-small currency shop.</p>
-
-<p>The library uses the tornado python library to handle HTTP and
-websocket connections, and provide a asynchronous system for
-connecting to and tracking several services. The code is available
-from
-<a href="http://github.com/petterreinholdtsen/valutakrambod">github</a>.</p>
-
-</p>There are two example clients of the library. One is very simple and
-list every updated buy/sell price received from the various services.
-This code is started by running bin/btc-rates and call the client code
-in valutakrambod/client.py. The simple client look like this:</p>
-
-<p><blockquote><pre>
-import functools
-import tornado.ioloop
-import valutakrambod
-class SimpleClient(object):
- def __init__(self):
- self.services = []
- self.streams = []
- pass
- def newdata(self, service, pair, changed):
- print("%-15s %s-%s: %8.3f %8.3f" % (
- service.servicename(),
- pair[0],
- pair[1],
- service.rates[pair]['ask'],
- service.rates[pair]['bid'])
- )
- async def refresh(self, service):
- await service.fetchRates(service.wantedpairs)
- def run(self):
- self.ioloop = tornado.ioloop.IOLoop.current()
- self.services = valutakrambod.service.knownServices()
- for e in self.services:
- service = e()
- service.subscribe(self.newdata)
- stream = service.websocket()
- if stream:
- self.streams.append(stream)
- else:
- # Fetch information from non-streaming services immediately
- self.ioloop.call_later(len(self.services),
- functools.partial(self.refresh, service))
- # as well as regularly
- service.periodicUpdate(60)
- for stream in self.streams:
- stream.connect()
- try:
- self.ioloop.start()
- except KeyboardInterrupt:
- print("Interrupted by keyboard, closing all connections.")
- pass
- for stream in self.streams:
- stream.close()
-</pre></blockquote></p>
-
-<p>The library client loops over all known "public" services,
-initialises it, subscribes to any updates from the service, checks and
-activates websocket streaming if the service provide it, and if no
-streaming is supported, fetches information from the service and sets
-up a periodic update every 60 seconds. The output from this client
-can look like this:</p>
-
-<p><blockquote><pre>
-Bl3p BTC-EUR: 5687.110 5653.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Hitbtc BTC-USD: 6594.560 6593.690
-Hitbtc BTC-USD: 6594.560 6593.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Hitbtc BTC-USD: 6594.570 6593.690
-Bitstamp EUR-USD: 1.159 1.154
-Hitbtc BTC-USD: 6594.570 6593.690
-Hitbtc BTC-USD: 6594.580 6593.690
-Hitbtc BTC-USD: 6594.580 6593.690
-Hitbtc BTC-USD: 6594.580 6593.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Paymium BTC-EUR: 5680.000 5620.240
-</pre></blockquote></p>
-
-<p>The exchange order book is tracked in addition to the best buy/sell
-price, for those that need to know the details.</p>
-
-<p>The other example client is focusing on providing a curses view
-with updated buy/sell prices as soon as they are received from the
-services. This code is located in bin/btc-rates-curses and activated
-by using the '-c' argument. Without the argument the "curses" output
-is printed without using curses, which is useful for debugging. The
-curses view look like this:</p>
-
-<p><blockquote><pre>
- Name Pair Bid Ask Spr Ftcd Age
- BitcoinsNorway BTCEUR 5591.8400 5711.0800 2.1% 16 nan 60
- Bitfinex BTCEUR 5671.0000 5671.2000 0.0% 16 22 59
- Bitmynt BTCEUR 5580.8000 5807.5200 3.9% 16 41 60
- Bitpay BTCEUR 5663.2700 nan nan% 15 nan 60
- Bitstamp BTCEUR 5664.8400 5676.5300 0.2% 0 1 1
- Bl3p BTCEUR 5653.6900 5684.9400 0.5% 0 nan 19
- Coinbase BTCEUR 5600.8200 5714.9000 2.0% 15 nan nan
- Kraken BTCEUR 5670.1000 5670.2000 0.0% 14 17 60
- Paymium BTCEUR 5620.0600 5680.0000 1.1% 1 7515 nan
- BitcoinsNorway BTCNOK 52898.9700 54034.6100 2.1% 16 nan 60
- Bitmynt BTCNOK 52960.3200 54031.1900 2.0% 16 41 60
- Bitpay BTCNOK 53477.7833 nan nan% 16 nan 60
- Coinbase BTCNOK 52990.3500 54063.0600 2.0% 15 nan nan
- MiraiEx BTCNOK 52856.5300 54100.6000 2.3% 16 nan nan
- BitcoinsNorway BTCUSD 6495.5300 6631.5400 2.1% 16 nan 60
- Bitfinex BTCUSD 6590.6000 6590.7000 0.0% 16 23 57
- Bitpay BTCUSD 6564.1300 nan nan% 15 nan 60
- Bitstamp BTCUSD 6561.1400 6565.6200 0.1% 0 2 1
- Coinbase BTCUSD 6504.0600 6635.9700 2.0% 14 nan 117
- Gemini BTCUSD 6567.1300 6573.0700 0.1% 16 89 nan
- Hitbtc+BTCUSD 6592.6200 6594.2100 0.0% 0 0 0
- Kraken BTCUSD 6565.2000 6570.9000 0.1% 15 17 58
- Exchangerates EURNOK 9.4665 9.4665 0.0% 16 107789 nan
- Norgesbank EURNOK 9.4665 9.4665 0.0% 16 107789 nan
- Bitstamp EURUSD 1.1537 1.1593 0.5% 4 5 1
- Exchangerates EURUSD 1.1576 1.1576 0.0% 16 107789 nan
- BitcoinsNorway LTCEUR 1.0000 49.0000 98.0% 16 nan nan
- BitcoinsNorway LTCNOK 492.4800 503.7500 2.2% 16 nan 60
- BitcoinsNorway LTCUSD 1.0221 49.0000 97.9% 15 nan nan
- Norgesbank USDNOK 8.1777 8.1777 0.0% 16 107789 nan
-</pre></blockquote></p>
-
-<p>The code for this client is too complex for a simple blog post, so
-you will have to check out the git repository to figure out how it
-work. What I can tell is how the three last numbers on each line
-should be interpreted. The first is how many seconds ago information
-was received from the service. The second is how long ago, according
-to the service, the provided information was updated. The last is an
-estimate on how often the buy/sell values change.</p>
-
-<p>If you find this library useful, or would like to improve it, I
-would love to hear from you. Note that for some of the services I've
-implemented a trading API. It might be the topic of a future blog
-post.</p>
-
-<p>As usual, if you use Bitcoin and want to show your support of my
-activities, please send Bitcoin donations to my address
-<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+ <title>What would it cost to store all 2018 phone calls in Norway?</title>
+ <link>http://people.skolelinux.org/pere/blog/What_would_it_cost_to_store_all_2018_phone_calls_in_Norway_.html</link>
+ <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/What_would_it_cost_to_store_all_2018_phone_calls_in_Norway_.html</guid>
+ <pubDate>Mon, 25 Nov 2019 20:15:00 +0100</pubDate>
+ <description><p>Four years ago, I did a back of the envelope calculation on
+<a href="http://people.skolelinux.org/pere/blog/What_would_it_cost_to_store_all_phone_calls_in_Norway_.html">how
+much it would cost to store audio recordings of all the phone calls in
+Norway</a>, and came up with NOK 2.1 million / EUR 250 000 for the
+year 2013. It is time to repeat the calculation using updated
+numbers. The calculation is based on how much data storage is needed
+for each minute of audio, how many minutes all the calls in Norway
+sums up to, multiplied by the cost of data storage.</p>
+
+<p>The number of phone call minutes for 2018 was fetched from
+<a href="https://ekomstatistikken.nkom.no/">the NKOM statistics
+site</a>, and for 2018, land line calls are listed as 434 238 000
+minutes, while mobile phone calls are listed with 7 542 006 000
+minutes. The total number of minutes is thus 7 976 244 000. For
+simplicity, I decided to ignore any advantages in audio compression the
+last four years, and continue to assume 60 Kbytes/min as the last
+time.</p>
+
+<p>Storage prices still varies a lot, but as last time, I decide to
+take a reasonable big and cheap hard drive, and double its price to
+include the surrounding costs into account. A 10 TB disk cost less
+than 4500 NOK / 450 EUR these days, and doubling it give 9000 NOK per
+10 TB.</p>
+
+<p>So, with the parameters in place, lets update the old table
+estimating cost for calls in a given year:</p>
+
+<table border="1">
+<tr><th>Year</th><th>Call minutes</th><th>Size</th><th>Price in NOK / EUR</th></tr>
+<tr><td>2005</td><td align="right">24 000 000 000</td><td align="right">1.3 PiB</td><td align="right">1 170 000 / 117 000</td></tr>
+
+<tr><td>2012</td><td align="right">18 000 000 000</td><td align="right">1.0 PiB</td><td align="right">900 000 / 90 000</td></tr>
+
+<tr><td>2013</td><td align="right">17 000 000 000</td><td align="right">950 TiB</td><td align="right">855 000 / 85 500</td></tr>
+
+<tr><td>2018</td><td align="right">7 976 244 000</td><td align="right">445 TiB</td><td align="right">401 100 / 40 110</td></tr>
+</table>
+
+<p>Both the cost of storage and the number of phone call minutes have
+dropped since the last time, bringing the cost down to a level where I
+guess even small organizations can afford to store the audio recording
+from every phone call taken in a year in Norway. Of course, this is
+just the cost of buying the storage equipment. Maintenance, need to
+be included as well, but the volume of a single year is about a single
+rack of hard drives, so it is not much more than I could fit in my own
+home. Wonder how much the electricity bill would raise if I had that
+kind of storage? I doubt it would be more than a few tens of thousand
+NOK per year.</p>
projects / homepage.git / blobdiff