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Tuesday, 30 September 2014

September 28th 2014 Weekly Bitcoin Network Statistics

Other weekly pool and network statistics posts


Welcome, miners.

Changelog:
  • Nil.

Errors:
  • Discus Fish still seem to update their data irregularly. Until they update more regularly, their data in the second table , and for figure 4, 5 and 7 will only be based on that subset.

Notifications:
  • Nil.

0. Private mining companies now account for 36% of the network.
I noticed that of the top seven places this week, one was for the unknowns, three for pools and three for known private companies. In all this accounts for 36% of the network. Pools are generally open about the blocks they've solved, and I would like to see companies like Megabigpower to follow the lead of Cointerra and sign all their blocks, not just some of them. Providing a list of solved blocks would be a nice step, too.

It's not a perfect system and people who care about the network's health will need to be vigilant and check that none of the "unknowns" can be attributable to a known mining company/pool, but as mining continues to centralise reducing the proportion of unknown blocks will become even more important to the network's health. Ideally, I would like to see it remain between 2% and 4% - enough for solominers to keep an anonymous piece of the action but not enough to allow any large known company to fifty-one percent the network (that's right, "fifty-one percent" is a verb now, just waiting for it to get into the Oxford English Dictionary"), or to significantly improve their "selfish mining" capacity.


1. Discus Fish and GHash.io battle royale part 4.
... and GHash.io gets the crown back.

2. Network contracted this week
The network hashrate is lower than it was last week and is actually the lowest (1078 blocks this week) it hash been since late July (1038 weekly blocks). Will we see a reduction in the network mining difficulty? The short answer is "no". The somewhat longer answer is "there will be no significant continued reduction in the network mining difficulty in the short term, even if the price halves" (I accept no responsibility for financial loss due to use of this information).

3. Got the new machine set up
I can hear it in the background, purring away quietly, not that screaming death rattle that the macbook used to have when I asked it to do anything more than just sit there and look pretty. Hopefully the money I spent on new machine will be money well spent.

Explanation of the tables and charts

Table 1: Solved block statistics. This table lists all statistics that can be derived from the number of blocks a hashrate contributor has solved for the past week. Block attributions are either from primary sources such as those claimed by a particular pool website, or secondary sources such as coinbase signatures, or known generation addresses. When dependent on secondary sources only, data may be inaccurate and miss some blocks if a particular block-solver has gone to some trouble to hide solved blocks. This will result in an underestimate of the block-solver hashrate.

Note that actual pool hashrates when derived from shares submitted per unit time will be more accurate than the hashrate estimates given in this table.

"Unknown" is not an entity but the group of blocks to which I cannot give attribution using the methods given above. "BitAffNet" is Bitcoin Affiliate Network.



Table 2: Pool reported block history statistics. This table lists all statistics that can be derived from the number of blocks a hashrate contributor has solved for the past week using all solved blocks - both valid and orphaned - and difficulty 1 shares per round. 
  • A much more accurate estimate of the hashrate, confidence intervals are unnecessary.
  • Orphan races lost, and percentage of  solved blocks that were not added to the blockchain.
  • "Luck" is the usual difficulty 1 equivalent shares per round / mining difficulty,  or (equivalently) accepted shares / expected shares.
  • CDF: The cumulative density function (CDF) measures the percentage of the time this number accepted shares / expected shares would be less than the calculated value, given the number of valid + invalid blocks.
  • Bitcoin per Gigashare. This figure is not an indicator of how much a miner should have expected per one billion Difficulty 1 shares (or one thousand difficulty megashares, etc), since it doesn't take into account the reward method or fees charged. Rather, it should be considered as a "luck" index that also incorporates the number of orphaned blocks and the current reward per block.
Since BTC Guild doesn't report shares per block but does report transaction hashes for all blocks, luck cannot be calculated but orphaned blocks can be enumerated. Pools that don't have a public pool interface cannot be included.



 Table 3: Reused but unknown generation addresses
Unknown generation addresses that are not reused are probably solominers or private mining concerns that don't have share-holders wanting to follow transactions. However, reused addresses are probably from hash contributors that do not wish to remain anonymous. These need to be identified so they can be removed from the "Unknown" group. I'm not interested in identifying those who wish to remain completely anonymous, so I'm not trying to trace originating IP addresses (as Blockchain.info does).

The table below includes unknown addresses that have been reused ever.


Table 3: Blocks solved by unknown but re-used generation addresses Sep 21 2014 to Sep 27 2014
Unknown recurring generation address Blocks solved this week Percentage of network Percentage of unknown Estimate of hashrate Blocks solved ever
1GcF7j3YH8Qs8hvNEe7zbrQZftMU6sRLfu 19 1.76 % 15.97 % 4128 Thps 172
19vvtxUpbidB8MT5CsSYYTBEjMRnowSZj4 15 1.39 % 12.61 % 3349 Thps 235
1FKK779mLcErfNFP8F3rgwGMztDGVWAsSq 14 1.30 % 11.76 % 2966 Thps 14
1BfNsApuHHfmoFx7H4mozJ3anLQit19bJ3 13 1.21 % 10.92 % 2857 Thps 13
18xf3MQvdVzKhyRvog8Q5P5THWvSjJUkzf 11 1.02 % 9.24 % 2433 Thps 19
1Ni2u5ex4sjrRQwu7fQsQDH4tc8pjwUrf 10 0.93 % 8.40 % 2461 Thps 14
1Db5jWADRY76C8JXKJArds1D3hQXFU112W 9 0.83 % 7.56 % 1907 Thps 9
16ikfC1dqJMarhjChdKvRizvdoSrMEjnsZ 8 0.74 % 6.72 % 1969 Thps 8
19oSdJmLUqrnrrMHMDeAvhkuPRZ1Kkh5js 8 0.74 % 6.72 % 1695 Thps 8
17xSk9HXHMeUJnZ3f9LYjcRHKBcmzzhWCx 6 0.56 % 5.04 % 1271 Thps 6
1Cpri8p1NGcQmV53vz2twDEUk3RXfEtqX7 3 0.28 % 2.52 % 738 Thps 3
18am2kwUXRotVDbtB69atxgB6DMgH6ERg7 1 0.09 % 0.84 % 212 Thps 6
1PNzs7ErcEPt8rM6rxJ8pVh4WBPGdoE3rL 1 0.09 % 0.84 % 246 Thps 2



Figure 1: Pie chart of the percentage of network blocks by pool A visual representation of the "Percentage of network" data aggregated in table 1.



Figure 2:  51% attack chart Historical hashrates of the bitcoin network, the largest mining pool, the three largest mining pools combined, and a line representing 50% of the network hashrate. Handy if you're worried about 51% attacks. Hashrates are all estimated from blocks solved, and the history goes back to the earliest date the data contains three known pools. Some pool data may be missing from the earliest data points. The upper and lower 95% confidence interval bounds for the network hashrate are in between the shaded areas. 


Figure 3: Percentage of blocks solved each week for the current top ten contributors
Data is calculated from the number of blocks each contributor added to the blockchain during the week. The points are the actual data; the lines are exponentiated smoothing splines of the log of the data.

Figure 4: Average hashrate per solved block (valid + invalid)
Hashrates are calculated from the pool reported difficulty 1 equivalent shares per round and the pool reported block solve times for all solved blocks, both valid and invalid. Note that BTC Guild is not included since the difficulty 1 equivalent shares per round data is not reported; instead use BTC Guild's hashrate chart which has matched my past estimates quite well and which I regard as accurate.

Figure 5: Pool "luck" (valid + invalid solved blocks)
The orange dots are the usual accepted shares / expected shares (equivalently, shares per round / network Difficulty). The background colours are accepted shares / expected shares confidence intervals for the number of blocks solved for the week. The greater the number of blocks solved (the higher the percentage of the network) the narrower the bounds.
The "luck" data points should be outside the upper or lower boundaries only rarely. Many data points outside this range indicate unusual and unlikely "luck".

Data only goes back for the last twelve months at most - any more data points than this becomes hard to read, and recent data is most important.

Note that all solved blocks are used, otherwise the data would no longer be Erlang distributed and a CDF could not be calculated.


Figure 6: Pool user hashrate and combined user hashrate densities
The top facet of this chart shows the proportion of user accounts with a given hashrate - the thicker the "violin" the greater the density of user accounts with a particular hashrate.

The bottom facet is the same data, weighted by hashrate. In effect, it shows what proportion of the pool's hashrate is supplied by particular hashrates. The area of the "violins" is proportional to their total hashrate.

Note that for some pools the hashrate is averaged over twenty four hours, some pools are averaged over an hour or more and some for only fifteen minutes, so expect some variance in the results.



Figure 7: Density of orphaned blocks
This chart shows the density of orphaned blocks per pool, as a function of blocks solved by that pool. The fringe indicates the actual occurrences of the orphaned blocks, and the colour of the line and fringe indicate the approximate date.

Some orphan data may be missing from Polmine. The rest seem to be correct.





Organofcorti lives!

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Thank you to blockchain.info and coinometrics.com for use of their transaction and address data, and coincadence.com for their p2pool miner data.

Find a typo or spelling error? Email me with the details at organofcorti@organofcorti.org and if you're the first to email me I'll pay you 0.01 btc per ten errors.

Please refer to the most recent blog post for current rates or rule changes.

I'm terrible at proofreading, so some of these posts may be worth quite a bit to the keen reader.
Exceptions:
  • Errors in text repeated across multiple posts: I will only pay for the most recent errors rather every single occurrence.
  • Errors in chart texts: Since I can't fix the chart texts (since I don't keep the data that generated them) I can't pay for them. Still, they would be nice to know about!
I write in British English.



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