Bitcoin Wiki - User contributions [en]

21bitcoin

2011-06-20T15:29:50Z

Nakowa:

[http://21bitcoin.com/pool 21bitcoin mining pool] is a HongKong based mining pool (web front located in US).

[http://21bitcoin.com/pool 21bitcoin 礦場] 是一個香港的礦場（網站前端設置在美國）。

Opened in June 20, 2011, 21bitcoin mining pool is grown up to the most vigorous mining pool in Chinese Netsphere.

於2011年6月20日正式開始運營，21bitcoin礦場正成爲中文網絡圈中最具活力的礦場。

[[Category:mining]]

21bitcoin

2011-06-20T15:26:15Z

Nakowa: Created page with "[http://21bitcoin.com/pool 21bitcoin mining pool] is a HongKong based mining pool (web front located in US). [http://21bitcoin.com/pool 21bitcoin 礦場] 是一個香港的礦..."

Comparison of mining pools

2011-06-20T15:17:16Z

Nakowa:

Reward types & explanation:
* '''MaxPPS''' - Maximum Pay Per Share. (summary needed)
* '''PPS''' - Pay Per Share. Each submitted share is worth certain amount of BTC. Since finding a block requires <current difficulty> shares ''on average'', a PPS method with 0% fee would be 50 BTC divided by <current difficulty>. It is risky for pool operators, hence the fee is highest.
* '''Prop.''' - Proportional. When block is found, the reward is distributed among all workers proportionally to how much shares each of them has found. This method is vulnerable to ''pool swapping'' cheat, where a worker would swap to another pool, if this one didn't find a block quickly. Then he would have extra profit on fast rounds, and normal profit on long rounds (because he would be mining on another pool by then). To mitigate this problem pools must introduce extra fees, and hide statistics, so that it is unknown when a block is found.
* '''Score''' - Score based system, the most advanced one. It is a proportional reward, but it is impossible to cheat as described above. Each submitted share is worth more in the function of time ''t'' since start of current round. For each share score is updated by: score += exp(t/C). This makes later shares worth more than earlier shares, thus swapping away to another pool on longer rounds makes the cheater's score to quickly diminish. Rewards are calculated proportionally to scores (and not to shares). Statistics can be shown "live" without fear. The score based method is perfect for 24/7 miners. (at slush's pool C=300 seconds, and every hour scores are normalized)

{| class="wikitable sortable"
|-
! Name !! Location !! Hashrate (GHash/sec)<ref name="hashrate">Hashrate is given in gigahash/second.</ref><ref name="hashrate2">Note that pool hashrate is largely irrelevant but can be seen as a popularity measurement. Note however that it is a theoretical security issue if one pool gains above 50% of the total computational power of the network, thus consider joining a pool based on other metrics.</ref> !! Reward Type !! Transaction fees !! Fee PPS !! Fee Prop / Score !! Audits<ref name="auditing">Auditing can be accomplished by third-parties if the pool publishes proofs-of-work for every share.</ref> !! Protocol !! Launched !! Forum Thread !! Homepage
|-
| [[21bitcoin|21bitcoin]] || CN, HK || 2 || Prop. || kept by pool || - || 0% || ? || RPC (+LP) || 2011-06-20 || [http://forum.bitcoin.org/index.php?topic=20056.0] || [http://21bitcoin.com/pool/ Link]
|-
| [[Bitclockers|BitClockers]] || USA, EU || 115 || Prop. || kept by pool || - || 1% || ? || RPC (+LP) || 2011-05-27 || [http://forum.bitcoin.org/index.php?topic=10127.0 Link] || [http://bitclockers.com/ Link]
|-
| [[Bitcoin_Pool|Bitcoin Mining Pool]] || USA || 255 || Prop. || kept by pool || - || 0%<ref name="donations">Donations are possible</ref> || ? || RPC (+LP) || Unknown || [http://bitcoinpool.com/forum/ Link] || [http://www.bitcoinpool.com/ Link]
|-
| [[Bitcoin_Pooled_Mining|Bitcoin Pooled Mining (Slush)]] || London || 1491 || Score || kept by pool || - || 2% || ? || RPC || 2010-11-27 || [http://forum.bitcoin.org/index.php?topic=1976.0 Link] || [http://mining.bitcoin.cz/ Link]
|-
| [[Bitcoins.lc]] || EU || 300 || Prop. || kept by pool || - || 0% || ? || RPC (+LP) || 2011-05-27 || [http://forum.bitcoin.org/index.php?topic=10121.0 Link] || [http://www.bitcoins.lc/ Link]
|-
| [[BitLotto Pool]] || Los Angeles || 1 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=13794.0 Link] || [http://www.bitlottopool.com/ Link]
|-
| [[BTC Guild]] || USA, EU || 1950|| Prop. || kept by pool || - || 0%<ref name="donationsf">Donations are possible to unlock features</ref>|| ? || RPC (+LP) || 2011-05-09 || [http://forum.bitcoin.org/index.php?topic=7760.0 Link] || [http://www.btcguild.com/ Link]
|-
| [[BTCMine]] || UK || 605 || Score || kept by pool || - || 2% || ? || RPC (+LP) || 2011-03-11 || [http://forum.bitcoin.org/index.php?topic=4251.0 Link] || [http://www.btcmine.com/ Link]
|-
| [[Continuum]] || Canada || 7 || PPS / Score || kept by pool || 5% || 0% || ? || RPC (+LP) || 2011-05-17 || [http://forum.bitcoin.org/index.php?topic=8660.0 Link] || [http://www.continuumpool.com/ Link]
|-
| [[DeepBit]] || Germany || 2661 || PPS / Prop. || kept by pool || 10% || 3% || ? || RPC (+LP) || 2011-02-26 || [http://forum.bitcoin.org/index.php?topic=3889.0 Link] || [http://deepbit.net/ Link]
|-
| [[Eclipse Mining Consortium]] || USA / Europe / AU / Asia || 25 || Prop / Score || kept by pool || 0% || 0% || ? || RPC (+LP) || 2011-06-14 || [http://forum.bitcoin.org/index.php?topic=16385.0 Link] || [https://eclipsemc.com Link]
|-
| [[Eligius]] || USA / Europe || 357 || MaxPPS / Prop. || kept by pool || ~0.0003%<ref name="donations">Donations are possible</ref> || ~0.0003%<ref name="donations">Donations are possible</ref> || Yes<ref name="auditnote">Access to Eligius proofs-of-work is available on request.</ref> || RPC (+LP) || 2011-04-27 || [http://forum.bitcoin.org/index.php?topic=6667.0 Link] || [http://eligius.st Link]
|-
| [[Mineco.in]] || UK || 35 || Prop || Shared || - || 0% || ? || RPC (+LP) || 2011-06-15 || [http://forum.bitcoin.org/index.php?topic=17310.0 Link] || [https://mineco.in/ Link]
|-
| [[Mining Team Reddit]] || USA, EU || 180 || Prop || kept by pool || - || 0%<ref name="donations">Donations are possible</ref> || ? || RPC (+LP) || 2011-05-25 || [http://forum.bitcoin.org/index.php?topic=15929.0 Link] || [http://www.mtred.com/ Link]
|-
| [[Ozco.in]] || AUS || 25 || Prop || Kept in Pool || 0% || 1% || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=14085.0/ Link] || [http://www.ozco.in Link]
|-
| [[Simplecoin]] || Unknown || 0 || Prop|| kept by pool || - || 0% || ? || RPC (+LP) || 2011-06-02 || [http://forum.bitcoin.org/index.php?topic=11186.0 Link] || [http://simplecoin.us/ Link]
|-
| [[Swepool]] || Sweden || 51 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-05-14 || [http://forum.bitcoin.org/index.php?topic=8288.0 Link] || [http://swepool.net/ Link]
|-
| [[x8s]] || Germany || 4 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=13275 Link] || [http://btc.x8s.de/ Link]
|-
| [[ZA Bitcoin]] || South Africa|| 0.4 || Score || kept by pool || 0% || 0% || ? || RPC (+LP) || 2011-06-14 || [http://forum.bitcoin.org/index.php?topic=17830.0 Link] || [http://www.zabitcoin.co.za/ Link]
|}

<references/>

== See also ==
*[[Pooled mining]]
*[http://bcx.me/ Bitcoin Mining Pool Tracker]

[[Category:Mining]]

Comparison of mining pools

2011-06-20T15:12:16Z

Nakowa:

Reward types & explanation:
* '''MaxPPS''' - Maximum Pay Per Share. (summary needed)
* '''PPS''' - Pay Per Share. Each submitted share is worth certain amount of BTC. Since finding a block requires <current difficulty> shares ''on average'', a PPS method with 0% fee would be 50 BTC divided by <current difficulty>. It is risky for pool operators, hence the fee is highest.
* '''Prop.''' - Proportional. When block is found, the reward is distributed among all workers proportionally to how much shares each of them has found. This method is vulnerable to ''pool swapping'' cheat, where a worker would swap to another pool, if this one didn't find a block quickly. Then he would have extra profit on fast rounds, and normal profit on long rounds (because he would be mining on another pool by then). To mitigate this problem pools must introduce extra fees, and hide statistics, so that it is unknown when a block is found.
* '''Score''' - Score based system, the most advanced one. It is a proportional reward, but it is impossible to cheat as described above. Each submitted share is worth more in the function of time ''t'' since start of current round. For each share score is updated by: score += exp(t/C). This makes later shares worth more than earlier shares, thus swapping away to another pool on longer rounds makes the cheater's score to quickly diminish. Rewards are calculated proportionally to scores (and not to shares). Statistics can be shown "live" without fear. The score based method is perfect for 24/7 miners. (at slush's pool C=300 seconds, and every hour scores are normalized)

{| class="wikitable sortable"
|-
! Name !! Location !! Hashrate (GHash/sec)<ref name="hashrate">Hashrate is given in gigahash/second.</ref><ref name="hashrate2">Note that pool hashrate is largely irrelevant but can be seen as a popularity measurement. Note however that it is a theoretical security issue if one pool gains above 50% of the total computational power of the network, thus consider joining a pool based on other metrics.</ref> !! Reward Type !! Transaction fees !! Fee PPS !! Fee Prop / Score !! Audits<ref name="auditing">Auditing can be accomplished by third-parties if the pool publishes proofs-of-work for every share.</ref> !! Protocol !! Launched !! Forum Thread !! Homepage
|-
| [[21bitcoin|21bitcoin]] || CN, HK || 2 || Prop. || kept by pool || - || 0% || ? || RPC (+LP) || 2011-06-20 || [] || [http://21bitcoin.com/pool/ Link]
|-
| [[Bitclockers|BitClockers]] || USA, EU || 115 || Prop. || kept by pool || - || 1% || ? || RPC (+LP) || 2011-05-27 || [http://forum.bitcoin.org/index.php?topic=10127.0 Link] || [http://bitclockers.com/ Link]
|-
| [[Bitcoin_Pool|Bitcoin Mining Pool]] || USA || 255 || Prop. || kept by pool || - || 0%<ref name="donations">Donations are possible</ref> || ? || RPC (+LP) || Unknown || [http://bitcoinpool.com/forum/ Link] || [http://www.bitcoinpool.com/ Link]
|-
| [[Bitcoin_Pooled_Mining|Bitcoin Pooled Mining (Slush)]] || London || 1491 || Score || kept by pool || - || 2% || ? || RPC || 2010-11-27 || [http://forum.bitcoin.org/index.php?topic=1976.0 Link] || [http://mining.bitcoin.cz/ Link]
|-
| [[Bitcoins.lc]] || EU || 300 || Prop. || kept by pool || - || 0% || ? || RPC (+LP) || 2011-05-27 || [http://forum.bitcoin.org/index.php?topic=10121.0 Link] || [http://www.bitcoins.lc/ Link]
|-
| [[BitLotto Pool]] || Los Angeles || 1 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=13794.0 Link] || [http://www.bitlottopool.com/ Link]
|-
| [[BTC Guild]] || USA, EU || 1950|| Prop. || kept by pool || - || 0%<ref name="donationsf">Donations are possible to unlock features</ref>|| ? || RPC (+LP) || 2011-05-09 || [http://forum.bitcoin.org/index.php?topic=7760.0 Link] || [http://www.btcguild.com/ Link]
|-
| [[BTCMine]] || UK || 605 || Score || kept by pool || - || 2% || ? || RPC (+LP) || 2011-03-11 || [http://forum.bitcoin.org/index.php?topic=4251.0 Link] || [http://www.btcmine.com/ Link]
|-
| [[Continuum]] || Canada || 7 || PPS / Score || kept by pool || 5% || 0% || ? || RPC (+LP) || 2011-05-17 || [http://forum.bitcoin.org/index.php?topic=8660.0 Link] || [http://www.continuumpool.com/ Link]
|-
| [[DeepBit]] || Germany || 2661 || PPS / Prop. || kept by pool || 10% || 3% || ? || RPC (+LP) || 2011-02-26 || [http://forum.bitcoin.org/index.php?topic=3889.0 Link] || [http://deepbit.net/ Link]
|-
| [[Eclipse Mining Consortium]] || USA / Europe / AU / Asia || 25 || Prop / Score || kept by pool || 0% || 0% || ? || RPC (+LP) || 2011-06-14 || [http://forum.bitcoin.org/index.php?topic=16385.0 Link] || [https://eclipsemc.com Link]
|-
| [[Eligius]] || USA / Europe || 357 || MaxPPS / Prop. || kept by pool || ~0.0003%<ref name="donations">Donations are possible</ref> || ~0.0003%<ref name="donations">Donations are possible</ref> || Yes<ref name="auditnote">Access to Eligius proofs-of-work is available on request.</ref> || RPC (+LP) || 2011-04-27 || [http://forum.bitcoin.org/index.php?topic=6667.0 Link] || [http://eligius.st Link]
|-
| [[Mineco.in]] || UK || 35 || Prop || Shared || - || 0% || ? || RPC (+LP) || 2011-06-15 || [http://forum.bitcoin.org/index.php?topic=17310.0 Link] || [https://mineco.in/ Link]
|-
| [[Mining Team Reddit]] || USA, EU || 180 || Prop || kept by pool || - || 0%<ref name="donations">Donations are possible</ref> || ? || RPC (+LP) || 2011-05-25 || [http://forum.bitcoin.org/index.php?topic=15929.0 Link] || [http://www.mtred.com/ Link]
|-
| [[Ozco.in]] || AUS || 25 || Prop || Kept in Pool || 0% || 1% || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=14085.0/ Link] || [http://www.ozco.in Link]
|-
| [[Simplecoin]] || Unknown || 0 || Prop|| kept by pool || - || 0% || ? || RPC (+LP) || 2011-06-02 || [http://forum.bitcoin.org/index.php?topic=11186.0 Link] || [http://simplecoin.us/ Link]
|-
| [[Swepool]] || Sweden || 51 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-05-14 || [http://forum.bitcoin.org/index.php?topic=8288.0 Link] || [http://swepool.net/ Link]
|-
| [[x8s]] || Germany || 4 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=13275 Link] || [http://btc.x8s.de/ Link]
|-
| [[ZA Bitcoin]] || South Africa|| 0.4 || Score || kept by pool || 0% || 0% || ? || RPC (+LP) || 2011-06-14 || [http://forum.bitcoin.org/index.php?topic=17830.0 Link] || [http://www.zabitcoin.co.za/ Link]
|}

<references/>

== See also ==
*[[Pooled mining]]
*[http://bcx.me/ Bitcoin Mining Pool Tracker]

[[Category:Mining]]

Comparison of mining pools

2011-06-20T15:10:57Z

Nakowa:

Reward types & explanation:
* '''MaxPPS''' - Maximum Pay Per Share. (summary needed)
* '''PPS''' - Pay Per Share. Each submitted share is worth certain amount of BTC. Since finding a block requires <current difficulty> shares ''on average'', a PPS method with 0% fee would be 50 BTC divided by <current difficulty>. It is risky for pool operators, hence the fee is highest.
* '''Prop.''' - Proportional. When block is found, the reward is distributed among all workers proportionally to how much shares each of them has found. This method is vulnerable to ''pool swapping'' cheat, where a worker would swap to another pool, if this one didn't find a block quickly. Then he would have extra profit on fast rounds, and normal profit on long rounds (because he would be mining on another pool by then). To mitigate this problem pools must introduce extra fees, and hide statistics, so that it is unknown when a block is found.
* '''Score''' - Score based system, the most advanced one. It is a proportional reward, but it is impossible to cheat as described above. Each submitted share is worth more in the function of time ''t'' since start of current round. For each share score is updated by: score += exp(t/C). This makes later shares worth more than earlier shares, thus swapping away to another pool on longer rounds makes the cheater's score to quickly diminish. Rewards are calculated proportionally to scores (and not to shares). Statistics can be shown "live" without fear. The score based method is perfect for 24/7 miners. (at slush's pool C=300 seconds, and every hour scores are normalized)

{| class="wikitable sortable"
|-
! Name !! Location !! Hashrate (GHash/sec)<ref name="hashrate">Hashrate is given in gigahash/second.</ref><ref name="hashrate2">Note that pool hashrate is largely irrelevant but can be seen as a popularity measurement. Note however that it is a theoretical security issue if one pool gains above 50% of the total computational power of the network, thus consider joining a pool based on other metrics.</ref> !! Reward Type !! Transaction fees !! Fee PPS !! Fee Prop / Score !! Audits<ref name="auditing">Auditing can be accomplished by third-parties if the pool publishes proofs-of-work for every share.</ref> !! Protocol !! Launched !! Forum Thread !! Homepage
|-
| [[21bitcoin|21bitcoin]] || CN, HK || 115 || Prop. || kept by pool || - || 0% || ? || RPC (+LP) || 2011-06-20 || [] || [http://21bitcoin.com/pool/ Link]
|-
| [[Bitclockers|BitClockers]] || USA, EU || 115 || Prop. || kept by pool || - || 1% || ? || RPC (+LP) || 2011-05-27 || [http://forum.bitcoin.org/index.php?topic=10127.0 Link] || [http://bitclockers.com/ Link]
|-
| [[Bitcoin_Pool|Bitcoin Mining Pool]] || USA || 255 || Prop. || kept by pool || - || 0%<ref name="donations">Donations are possible</ref> || ? || RPC (+LP) || Unknown || [http://bitcoinpool.com/forum/ Link] || [http://www.bitcoinpool.com/ Link]
|-
| [[Bitcoin_Pooled_Mining|Bitcoin Pooled Mining (Slush)]] || London || 1491 || Score || kept by pool || - || 2% || ? || RPC || 2010-11-27 || [http://forum.bitcoin.org/index.php?topic=1976.0 Link] || [http://mining.bitcoin.cz/ Link]
|-
| [[Bitcoins.lc]] || EU || 300 || Prop. || kept by pool || - || 0% || ? || RPC (+LP) || 2011-05-27 || [http://forum.bitcoin.org/index.php?topic=10121.0 Link] || [http://www.bitcoins.lc/ Link]
|-
| [[BitLotto Pool]] || Los Angeles || 1 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=13794.0 Link] || [http://www.bitlottopool.com/ Link]
|-
| [[BTC Guild]] || USA, EU || 1950|| Prop. || kept by pool || - || 0%<ref name="donationsf">Donations are possible to unlock features</ref>|| ? || RPC (+LP) || 2011-05-09 || [http://forum.bitcoin.org/index.php?topic=7760.0 Link] || [http://www.btcguild.com/ Link]
|-
| [[BTCMine]] || UK || 605 || Score || kept by pool || - || 2% || ? || RPC (+LP) || 2011-03-11 || [http://forum.bitcoin.org/index.php?topic=4251.0 Link] || [http://www.btcmine.com/ Link]
|-
| [[Continuum]] || Canada || 7 || PPS / Score || kept by pool || 5% || 0% || ? || RPC (+LP) || 2011-05-17 || [http://forum.bitcoin.org/index.php?topic=8660.0 Link] || [http://www.continuumpool.com/ Link]
|-
| [[DeepBit]] || Germany || 2661 || PPS / Prop. || kept by pool || 10% || 3% || ? || RPC (+LP) || 2011-02-26 || [http://forum.bitcoin.org/index.php?topic=3889.0 Link] || [http://deepbit.net/ Link]
|-
| [[Eclipse Mining Consortium]] || USA / Europe / AU / Asia || 25 || Prop / Score || kept by pool || 0% || 0% || ? || RPC (+LP) || 2011-06-14 || [http://forum.bitcoin.org/index.php?topic=16385.0 Link] || [https://eclipsemc.com Link]
|-
| [[Eligius]] || USA / Europe || 357 || MaxPPS / Prop. || kept by pool || ~0.0003%<ref name="donations">Donations are possible</ref> || ~0.0003%<ref name="donations">Donations are possible</ref> || Yes<ref name="auditnote">Access to Eligius proofs-of-work is available on request.</ref> || RPC (+LP) || 2011-04-27 || [http://forum.bitcoin.org/index.php?topic=6667.0 Link] || [http://eligius.st Link]
|-
| [[Mineco.in]] || UK || 35 || Prop || Shared || - || 0% || ? || RPC (+LP) || 2011-06-15 || [http://forum.bitcoin.org/index.php?topic=17310.0 Link] || [https://mineco.in/ Link]
|-
| [[Mining Team Reddit]] || USA, EU || 180 || Prop || kept by pool || - || 0%<ref name="donations">Donations are possible</ref> || ? || RPC (+LP) || 2011-05-25 || [http://forum.bitcoin.org/index.php?topic=15929.0 Link] || [http://www.mtred.com/ Link]
|-
| [[Ozco.in]] || AUS || 25 || Prop || Kept in Pool || 0% || 1% || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=14085.0/ Link] || [http://www.ozco.in Link]
|-
| [[Simplecoin]] || Unknown || 0 || Prop|| kept by pool || - || 0% || ? || RPC (+LP) || 2011-06-02 || [http://forum.bitcoin.org/index.php?topic=11186.0 Link] || [http://simplecoin.us/ Link]
|-
| [[Swepool]] || Sweden || 51 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-05-14 || [http://forum.bitcoin.org/index.php?topic=8288.0 Link] || [http://swepool.net/ Link]
|-
| [[x8s]] || Germany || 4 || Prop || kept by pool || - || - || ? || RPC (+LP) || 2011-06-08 || [http://forum.bitcoin.org/index.php?topic=13275 Link] || [http://btc.x8s.de/ Link]
|-
| [[ZA Bitcoin]] || South Africa|| 0.4 || Score || kept by pool || 0% || 0% || ? || RPC (+LP) || 2011-06-14 || [http://forum.bitcoin.org/index.php?topic=17830.0 Link] || [http://www.zabitcoin.co.za/ Link]
|}

<references/>

== See also ==
*[[Pooled mining]]
*[http://bcx.me/ Bitcoin Mining Pool Tracker]

[[Category:Mining]]

Pooled mining

2011-06-20T15:08:04Z

Nakowa: /* External links */

'''Pooled mining''' is an approach where multiple generating clients contribute to the generation of a block, and then split the block reward according the contributed processing power. Pooled mining effectively reduces the granularity of the block generation reward, spreading it out more smoothly over time.

==Introduction==

With increasing generation difficulty, mining with lower-performance devices can take a very long time before block generation, on average. For example, with a mining speed of 1000 Khps, at a difficulty of 14484 (which was in effect at the end of December, 2010), the average time to generate a block is almost 2 years.

To provide a more smooth incentive to lower-performance miners, several pooled miners, using different approaches, have been created. With a mining pool, a lot of different people contribute to generating a block, and the reward is then split among them according to their processing contribution. This way, instead of waiting for years to generate 50btc in a block, a smaller miner may get a fraction of a bitcoin on a more regular basis.

A '''share''' is awarded by the mining pool to the clients who present a valid [[proof of work]] of the same type as the proof of work that is used for creating [[block|blocks]], but of lesser complexity, so that it requires less time on average to generate.

==Pooled mining approaches==

The problem with pooled mining is that steps must be taken to prevent cheating by the clients and the server. Currently there are two different approaches used.

===The slush approach===

[[Bitcoin Pooled Mining]] (BPM), sometimes referred to as "slush's pool", follows a score-based method. Older shares (from beginning of the round) has lower weight than newer shares, which demotivate cheater from switching between pools inside one round.

===The puddinpop approach===

(As of February, 2011, there are no puddinpop pools running.)

Another approach is the 'metahash' technique, used by puddinpop's [[remote miner]]. Clients generate hashes, and also submit 'metahashes', which are hashes of a large chunk of generated hashes. The server checks that the metahashes are correct (in a round-robin fashion, picking up a metahash from a client that hasn't been checked on the longest), thus preventing clients from simply claiming that they have done work without actually doing the work. The withholding of good blocks by the clients is prevented via the server being in possession of the private key, just as in the previous approach. Rewards are distributed based on the number of metahashes submitted by the clients.

The generated blocks contain multiple keys in the generation transaction, giving fractional bitcoin amounts to each key, in proportion to their hashing contribution for that block.

===The BitPenny approach===

The [[BitPenny]] approach is to offer an instant, flat payout for each share that is solved. The payout is offered from the pool's existing balance and can therefore be withdrawn immediately, without waiting for a block to be solved or confirmed. The possibility of cheating by the pool operator and by timing attacks is thus completely eliminated.

This method results in the least possible variance for miners while transferring all risk to the pool operator. The resulting possibility of loss for the server is offset by setting the payout lower than the full expected value.

===Luke-Jr's approach ("[[Eligius]]")===
[[User:Luke-Jr|Luke]] came up with a third approach borrowing strengths from the earlier two.
Like slush's approach, miners submit proofs-of-work to earn shares.
Like puddinpop's approach, the pool pays out immediately via block generation.
When distributing block rewards, it is divided equally among all shares since the last valid block.
Unlike any preexisting pool approach, this means that the shares contributed toward orphaned blocks are recycled into the next block's shares.
In order to spare participating miners from transaction fees, rewards are only paid out if a miner has earned at least 1 BTC. If the amount owed is less, it will be added to the earnings of a later block (which may then total over 1 BTC).
If a miner does not submit a share for over a week, the pool sends any balance remaining, regardless of its size.

===Comparison===

The cooperative mining approach (slush and Luke-Jr) uses a lot less resources on the pool server, since rather than continuously checking metahashes, all that has to be checked is the validity of submitted shares. The number of shares sent can be adjusted by adjusting the artificial difficulty level.

Further, the cooperative mining approach allows the clients to use existing miners without any modification, while the puddinpop approach requires the custom pool miner, which are as of now not as efficient on GPU mining as the existing GPU miners.
[[File:Smallgeneration.png|thumb|Puddinpop miners receive coins directly.]]

Additionally, the puddinpop and Luke-Jr approaches of distributing the earnings by way of including precise sub-cent amounts in the generation transaction for the participants, results in the presence of sub-cent bitcoin amounts in your wallet, which are liable to disappear (as unnecessary fees) later due to a bug in old (before 0.3.21) bitcoin nodes. (E.g., if you have a transaction with 0.052 in your wallet, and you later send .05 to someone, your .002 will disappear.).

Puddinpop and Luke-Jr miners receive coins directly, which eliminates the delay in receiving earnings that is required on slush-based mining servers. However, earnings sent directly to some services like MyBitcoin and MtGox will not be accounted for.

==See Also==

* [[:Category:Miners|Miners]]
* [[Comparison of mining pools]]
* [[:Category:Pool Operators|Pool Operators]]
* [[Why a GPU mines faster than a CPU]]
* [[Why pooled mining]]
* [[Mining pool reward FAQ]]

==External links==

* [http://21bitcoin.com/pool/ 21bitcoin mining pool, Chinese Interface]
* [http://mining.bitcoin.cz slush's mining pool]
* [http://www.bitcoin.org/smf/index.php?topic=1458.0 puddinpop's mining pool thread]
* [http://blockexplorer.com/block/00000000000233334b157d901714baf59e5b9236227b2878844e52244da4195e example puddinpop block]
* [http://bitclockers.com bitclockers mining pool]

==References==
<references />

[[Category:Mining]]