March 23rd 2014 Weekly Hashrate Contributor and Network Statistics

Other weekly pool and network statistics posts


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0. Private vs public hashing.
The number of blocks solved by the network each week hash been slowly reducing, from the 1200 to 1300 blocks per week of previous months to the current 1100 blocks per week. GHash.IO still commands about two sevenths of the network, and since the KNC solomining operation moved out of Eligius (taking ten percent of the network with them) BTCGuild and Eligius have been sharing two sevenths of the network between them. The 500TH mine seems to have moved to BTCGuild, probably due to variance from their low hashrate.

Ghash.IO has an unknown proportion of private hashing; of the remaining five sevenths of the network only two thirds are in the hands of public pools. This level of private hashing is something that has been expected but I didn't really notice it until now. I expect I'll need to start following this.


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 from either coinbase signatures, known generation addresses or claimed by a particular pool block history. Includes non-Pool hashrate contributors. 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 simply the group of blocks to which I cannot give attribution using the methods given above.

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 such as "Discus Fish" 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).

Table 3: Blocks solved by unknown but re-used generation addresses Mar 16 2014 to Mar 22 2014

Unknown recurring generation address	Blocks solved this week	Percentage of network	Percentage of unknown	Estimate of hashrate	Blocks solved ever
1GzJciogpbihQ2z4nfSp9rPro8RYvKn8DB	16	1.37 %	19.51 %	483 Thps	34
19fEZNP879ZyrvtohYATUynkwdzNbDMfGq	9	0.77 %	10.98 %	272 Thps	20
1K7znxRfkS8R1hcmyMvHDum1hAQreS4VQ4	8	0.68 %	9.76 %	241 Thps	94
1HM1PXxUGgDXaLB4JWT8CxCZkj9Y9G5rB5	3	0.26 %	3.66 %	91 Thps	9
1Px9MwafHR1N7ugmGKw556xf2rrmPAtza3	2	0.17 %	2.44 %	60 Thps	3
1BBdQezhQox3BKfJd5Jv84A948fg3SqVJS	1	0.09 %	1.22 %	30 Thps	3

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.

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