Bitcoin mining pools

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Bitcoin Mining?

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Mining Pools

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Mining pools are a way for miners to pool their resources together and share their hashing power while splitting the reward equally according to the amount of shares they contributed to solving a block. A "share" is awarded to members of the mining pool who present a valid proof of work that their miner solved. Mining in pools began when the difficulty for mining increased to the point where it could take years for slower miners to generate a block. The solution to this problem was for miners to pool their resources so they could generate blocks quicker and therefore receive a portion of the block reward on a consistent basis, rather than randomly once every few years.

Mining Pools

There are many good mining pools to choose from. Although it's tempting to pick the most popular one, it's better for the health of the network to mine with smaller pools so as to avoid potentially harmful concentration of hashing power. To see the relative size of any given pool, check blockchain.info's pool pie chart .

For a fully decentralized pool, we recommend p2pool .

A comparison list of all mining pools can be found here .

Pool Payment Methods

Calculating your share of the coins mined can be complex. In an ongoing effort to come up with the fairest method and prevent gaming of the system, many calculation schemes have been invented. The two most popular types are PPS and DGM. PPS, or 'pay per share' shifts the risk to the pool while they guarantee payment for every share you contribute. PPS payment schemes require a very large reserve of 10,000 BTC in order to ensure they have the means of enduring a streak of bad luck. For this reason, most pools no longer support it. One of the few remaining PPS pools is EclipseMC. DGM is a popular payment scheme because it offers a nice balance between short round and long round blocks. However, end users must wait for full round confirmations long after the blocks are processed.

PPS: The Pay-per-Share (PPS) approach offers an instant, guaranteed payout for each share that is solved by a miner. Miners are paid out from the pools existing balance and can withdraw their payout immediately. This model allows for the least possible variance in payment for miners while also transferring much of the risk to the pool's operator.

PROP: The Proportional approach offers a proportional distribution of the reward when a block is found amongst all workers, based off of the number of shares they have each found.

PPLNS: The Pay Per Last N Shares (PPLN) approach is similar to the proportional method, but instead of counting the number of shares in the round, it instead looks at the last N shares, no matter the boundaries of the round.

DGM: The Double Geometric Method (DGM) is a hybrid approach that enables the operator to absorb some of the risk. The operator receives a portion of payouts during short rounds and returns it during longer rounds to normalize payments.

SMPPS: The Shared Maximum Pay Per Share (SMPPS) uses a similar approach to PPS but never pays more than the pool has earned.

ESMPPS: The Equalized Shared Maximum Pay Per Share (ESMPPS) is similar to SMPPS, but distributes payments equally among all miners in the pool.

RSMPPS: The Recent Shared Maximum Pay Per Share (RSMPPS) is also similar to SMPPS, but the system prioritizes the most recent miners first.

CPPSRB: The Capped Pay Per Share with Recent Backpay uses a Maximum Pay Per Share (MPPS) reward system that will pay miners as much as possible using the income from finding blocks, but will never go bankrupt.

BPM: Bitcoin Pooled mining (BPM), also known as "slush's pool", uses a system where older shares from the beginning of a block round are given less weight than more recent shares. This reduces the ability to cheat the mining pool system by switching pools during a round.

POT: The Pay on Target (POT) approach is a high variance PPS that pays out in accordance with the difficulty of work returned to the pool by a miner, rather than the difficulty of work done by the pool itself.

SCORE: The SCORE based approach uses a system whereby a proportional reward is distributed and weighed by the time the work was submitted. This process makes later shares worth more than earlier shares and scored by time, thus rewards are calculated in proportion to the scores and not shares submitted.

ELIGIUS: Eligius was designed by Luke Jr. creator of BFGMiner, to incorporate the strengths of PPS and BPM pools, as miners submit proofs-of-work to earn shares and the pool pays out immediately. When the block rewards are distributed, they are divided equally among all shares since the last valid block and the shares contributed to stale blocks are cycled into the next block's shares. Rewards are only paid out if a miner earns at least .67108864 and if the amount owed is less than that it will be rolled over to the next block until the limit is achieved. However, if a miner does not submit a share for over a period of a week, then the pool will send any remaining balance, regardless of its size.

Triplemining: Triplemining brings together medium-sized pools with no fees and redistributes 1% of every block found, which allows your share to grow faster than any other pool approach. The administrators of these pools use some of the Bitcoins generated when a block is found to add to a jackpot that is triggered and paid out to the member of the pool who found the block. In this way, everyone in the pool has a better chance to make additional Bitcoins, regardless of their processing power.

Quick updates

02.02.2014

Datacenter connectivity issues have caused short drop in the hashrate. The problem has been resolved and all stratum servers are now reachable. This all happened when 900 Th/s was within a reach. We will get there again with your support and participation in mining ;-)

17.01.2014

We were having an extremely lucky yesterday's mining session. Unfortunately, around 1.30 AM UTC, we were experiencing stratum server issues that eventually spread across all our stratum servers. The problem has been resolved now and mining continues.

13.01.2014

The pool database backend has been successfully migrated to a new hardware. The website is now fully operational. The whole migration process has been accomplished without interrupting the actual mining.

13.01.2014

We are currently migrating pool database to a new machine. Mining will continue without interruption, only website will be down for 1-2 hours.

18.12.2013

Some recent payouts didn't go thru bitcoin network because of unsatisfied transaction fees. We're finding a soluton and all payouts will be processed soon

16.10.2013

In recent days we experienced some successful thefts of user's funds using compromised email accounts. We strongly encourage all users to change email passwords. There's no reason to think that pool security itself has been compromised.

08.07.2013

Getwork protocol support ended. Please be sure your miners support Stratum protocol. You can still use your old getwork miners with Stratum proxy installed on your mining rig.

21.05.2013

Bug in bitcoind caused many invalid blocks generated in recent hours. Thanks to cooperation with bitcoin developers, a bugfix has been deployed. Pool is now back in normal operation.

26.04.2013

Because the user database has been compromised in recent hack, please change password to your pool account!

25.04.2013

Pool is recovering to normal operation from previous attack. delayed payouts will be processed in the afternoon (UTC).

18.04.2013

Pool is recovering from DDoS attack.

14.04.2013

As announced in Getwork deprecation plan. the hashrate on Stratum is far above 90%, so workers which are still using the deprecated Getwork protocol are now charged by 10% fee. Please update your software and start using modern Stratum miners to reduce your fees back to 2%!

12.03.2013

Bitcoin network recently experienced global problems which caused some pool blocks to be invalid. Everything seems to be fixed now.

10.03.2013

Default mining URL for Stratum is stratum.bitcoin.cz:3333 . If you're still using api.bitcoin.cz, please fix your URL to prevent fallback to deprecated Getwork protocol.

08.03.2013

Stratum proxy version 1.5.2 has been released. This is bugfix release which add compatibility with some old miners (phoenix, Diablo).

03.03.2013

Stratum proxy version 1.5.0 has been released. All proxy users are encouraged to update .

13.02.2013

ASIC mining become a reality. Jeff Garzik (bitcoin core developer) is testing first shipped unit of Avalon ASIC miner on our pool.

30.01.2013

Native IPv6 address is now available. You can use ipv6.stratum.bitcoin.cz:3333 in your miner if your miners have IPv6 support! Please note that IPv6 works only for Stratum miners.

08.12.2012

If you're using old miners from early 2011 or you're mining on URL "mining.bitcoin.cz:8332", please update your miners and use "api.bitcoin.cz:8332" in your configuration instead. Mining on URL "mining.bitcoin.cz" is not working anymore.

27.11.2012

Only one day remains to halving block reward from 50 BTC to 25 BTC. Thanks to this change in Bitcoin world, mining income will be drastically reduced. As a countermeasure, pool is now paying block fees to miners. Everything you need to collect block fees is to use miner with Stratum support .

24.11.2012

Pool is now giving transaction fees to Stratum miners! Use miner with Stratum support (latest version of GUIminer, cgminer, bfgminer, poclbm) or use your favourite miner with Stratum proxy to improve your mining income!

19.11.2012

Guiminer with Stratum support has been released. Upgrade is highly recommended.

12.10.2012

All users are encouraged to install or update Stratum proxy to current stable version 1.1.1. Instructions are here .

12.10.2012

New version of cgminer has been released. Please update cgminer to version 2.8.3 . which fixes serious bugs introduced in previous versions.

10.10.2012

In effect from 01.11.2012, pool increases the lower limit for payouts ("send threshold") to 0.05 BTC (around $0.6) as a protection against high transaction fees for tiny payouts. If you have a balance of less than 0.05 BTC and want to withdraw them, please do so before November 1.

20.09.2012

New version of poclbm miner has been released. All poclbm users are encouraged to update their miner, latest version includes major optimization.

11.09.2012

I'm seeking for beta testers of new mining protocol called Stratum mining. If you want to join testing, please download the proxy and point your miners to it. Thank you!

08.07.2012

Do you have some bitcoins from the mining and do you want to sell them for cheap? Add your offer to localbitcoins.com and find a buyer in your neighborhood!

11.06.2012

Follow pool's page for recent updates and news!

05.02.2012

poclbm/GUI miner is affected by serious bug. If your miner is crashing on 'unexpected error' message, please follow miner forums for the newest versions.

26.01.2012

Pool is now supporting BIP 16 protocol extension, as described here. It is just internal change on the Bitcoin network, miners don't need to update anything.

08.11.2011

Implemented prioritization of long polling. Fast miners should expect lower stale ratio.

10.10.2011

Merged mining for Namecoins added. Please fill NMC address on your profile to start collecting Namecoins! Accounting isn't finished yet, but will come very soon.

03.10.2011

Bitcoin.cz is official sponsor of European Bitcoin conference 2011. See you on 25.-27. November in Prague!

26.03.2011

Second server added

Total hashrate at 60Ghash/s

19.01.2011

We're over 20 Ghash/s

20.12.2010

Technical Background more »

During mining, your computer runs a cryptographic hashing function (two rounds of SHA256) on what is called a block header . For each new hash, the mining software will use a different number as the random element of the block header, this number is called the nonce . Depending on the nonce and what else is in the block the hashing function will yield a hash which looks like this:

You can look at this hash as a really long number. (It's a hexadecimal number, meaning the letters A-F are the digits 10-15.) Now to make mining difficult, there is what's called a difficulty target . To create a valid block your miner has to find a hash that is below the difficulty target. So if for example the difficulty target is 1000000000000000000000000000000000000000000000000000000000000000, any number that starts with a zero would be below the target, e.g.:

If we lower the target to 0100000000000000000000000000000000000000000000000000000000000000, we now need two zeros in the beginning to be under it:

Because the target is such an unwieldy number with tons of digits, people generally use a simpler number to express the current target. This number is called the mining difficulty . The mining difficulty expresses how much harder the current block is to generate compared to the first block. So a difficulty of 70000 means to generate the current block you have to do 70000 times more work than Satoshi had to do generating the first block. Though be fair though, back then mining was a lot slower and less optimized.

The difficulty changes every 2016 blocks. The network tries to change it such that 2016 blocks at the current global network processing power take about 14 days. That's why, when the network power rises, the difficulty rises as well.

Bitcoin Mining Hardware

CPU's: In the beginning, mining with a CPU was the only way to mine bitcoins. Mining this way via the original Satoshi client is how the bitcoin network started. This method is no longer viable now that the network difficulty level is so high. You might mine for years and years without earning a single coin.

GPU's: Soon it was discovered that high end graphics cards were much more efficient at bitcoin mining and the landscape changed. CPU bitcoin mining gave way to the GPU (Graphical Processing Unit). The massively parallel nature of some GPUs allowed for a 50x to 100x increase in bitcoin mining power while using far less power per unit of work. While any modern GPU can be used to mine, the AMD line of GPU architecture turned out to be far superior to the nVidia architecture for mining bitcoins and the ATI Radeon HD 5870 turned out to be the most cost effective choice at the time.

FPGA's: As with the CPU to GPU transition, the bitcoin mining world progressed up the technology food chain to the Field Programmable Gate Array. With the successful launch of the Butterfly Labs FPGA ‘Single', the bitcoin mining hardware landscape gave way to specially manufactured hardware dedicated to mining bitcoins. While the FPGAs didn't enjoy a 50x - 100x increase in mining speed as was seen with the transition from CPUs to GPUs, they provided a benefit through power efficiency and ease of use. A typical 600 MH/s graphics card consumed upwards of 400w of power, whereas a typical FPGA mining device would provide a hashrate of 826 MH/s at 80w of power. That 5x improvement allowed the first large bitcoin mining farms to be constructed at an operational profit. The bitcoin mining industry was born.

ASIC's: The bitcoin mining world is now solidly in the Application Specific Integrated Circuit (ASIC) era. An ASIC is a chip designed specifically to do one thing and one thing only. Unlike FPGA's, an ASIC cannot be repurposed to perform other tasks. An ASIC designed to mine bitcoins can only mine bitcoins and will only ever mine bitcoins. The inflexibility of an ASIC is offset by the fact that it offers a 100x increase in hashing power while reducing power consumption compared to all the previous technologies. For example, a good bitcoin miner like the Monarch from Butterfly Labs provides 600 GH/s (1 Gigahash is 1000 Megahash. 1 GH/s = 1000 MH/s) while consuming 350w of power. Compared to the GPU era, this is an increase in hashrate and power savings of nearly 300x. (Calculate the earnings of any bitcoin mining hardware device using this bitcoin mining calculator ).

Unlike all the previous generations of hardware preceding ASIC, ASIC is the "end of the line" when it comes to disruptive technology. CPUs were replaced by GPUs which were in turn replaced by FPGAs which were replaced by ASICs. There is nothing to replace ASICs now or even in the immediate future. There will be stepwise refinement of the ASIC products and increases in efficiency, but nothing will offer the 50x - 100x increase in hashing power or 7x reduction in power usage that moves from previous technologies offered. This makes power consumption on an ASIC device the single most important factor of any ASIC product, as the expected useful lifetime of an ASIC mining device is longer than the entire history of bitcoin mining. It is conceivable that an ASIC device purchased today would still be mining in two years if the device is power efficient enough and the cost of electricity does not exceed it's output. Mining profitability is also dictated by the exchange rate, but under all circumstances the more power effecient the mining device, the more profitable it is.

Software

There are two basic ways to mine: On your own or as part of a pool. Almost all miners choose to mine on a pool because it takes the luck out of the process. Before you join a pool, make sure you have a bitcoin wallet so you have a place to store your bitcoins. Next you need to join a mining pool like Eclipse. Eligius or BTC Guild. With pool mining, the profit from any block a member generates is divided up among the members of the pool. This gives the pool members a more frequent, steady payout (this is called reducing your variance), but your payout(s) will be less unless you use a zero fee pool like Eclipse. Solo mining will give you large, infrequent payouts and pooled mining will give you small, frequent payouts, but both add up to the same amount if you're using a zero fee pool.

Once you have your client set up or you have registered with a pool, the next step is to set up the actual mining software. The most popular GPU/FPGA/ASIC miner at the moment is BFGminer or CGminer. For a full GUI experience, try EasyMiner .

If you want a quick taste of mining without installing any software, try Bitcoin Plus. a browser-based CPU Bitcoin miner. As a CPU miner it's not cost-efficient for serious mining, but it does illustrate the principle of pooled mining very well.

Thanks to:

Blitzboom and the guys from #bitcoin-dev for their help with writing the guide!

Beginners Guide to Mining Bitcoins

One of the biggest problems I ran into when I was looking to start mining Bitcoin for investment and profit was most of the sites were written for the advanced user. I am not a professional coder, I have no experience with Ubuntu, Linux and minimal experience with Mac. So, this is for the individual or group that wants to get started the easy way.

First thing you need to do is get a “Bitcoin Wallet”. Because Bitcoin is an internet based currency, you need a place to keep your Bitcoins. Got to http://www.bitcoin.org and download the Bitcoin client for your Operating System. Install it the client will begin to download the blockchain. Downloading the blockchain can take a long time and will be over 6GB of data. If you have data caps, I would recommend ordering a copy of the blockchain on DVD to keep from going over as it is growing exponentially. Click to order the bitcoin blockchain by mail. Once the client is up to date, click “New” to get your wallet address. It will be a long sequence of letters and numbers. One of most important things you can do is make sure you have a copy of the wallet.dat file on a thumb drive and print a copy out and keep it in a safe location. You can view a tutorial on how to create a secure wallet by clicking the link on the top of the page. The reason is that if you computer crashes and you do not have a copy of your wallet.dat file, you will lose all of your Bitcoins. They won’t go to someone else, they will disappear forever. It is like burning cash.

Now that you have a wallet and the client, you are probably roaring to go, but if you actually want to make Bitcoin (money), you probably need to join a pool. A pool is a group that combines their computing power to make more Bitcoins. The reason you shouldn’t go it alone is that Bitcoins are awarded in blocks, usually 50 at a time, and unless you get extremely lucky, you will not be getting any of those coins. In a pool, you are given smaller and easier algorithms to solve and all of your combined work will make you more likely to solve the bigger algorithm and earn Bitcoins that are spread out throughout the pool based on your contribution. Basically, you will make a more consistent amount of Bitcoins and will be more likely to receive a good return on your investment.

The pool that I’m involved in is called Slush’s Pool so I will be giving instructions on how to join there but feel free to look at other options. Follow the link to go to their site and click the “Sign up here” link at the top of their site and follow their step by step instructions. After you have your account set up, you will need to add a “Worker”. Basically, for every miner that you have running, you will need to have a worker ID so the pool can keep track of your contributions.

If you are mining with an ASIC, please go to our Mining with ASICs page. The following will only pertain to GPU miners.

Most of the mining programs out there are pretty complicated to setup and will frustrate your average user. Recently a great program has come out to get the most basic of users started. The program is called GUIMiner. Click the link and download the program (Be careful, some of the ads are set up to look like the file download). Install and run the program and add in your information from Slush’s Pool. Remember that the user name is actually the worker name. The worker name will be your user name, dot, worker ID (username.worker ID) and the password from that worker ID.

Mac users should look into using Astroid

Now that you are set up, you can start mining. If you feel like you want to make more Bitcoins, you might want to invest in mining hardware.

To see how much your current hardware will earn mining Bitcoins, head over to the Bitcoin Profitability Calculator .

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