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When I mine to a pool, how does the pool calculate my hashrate or my payout?

  • Staff

    What’s a share?

    A share is a unit of reward that miners earn by submitting proofs of work (the result of hashing) to the pool. The term “share” originates from the reward system of proportional pools, whose total earnings are distributed among miners in proportion to the number of shares they submit. In a PPS (pay-per-share) system, shares are paid directly to miners, indipendently of how many blocks the pool actually finds. The value of a share depends on two factors: the network difficulty and the share difficulty.

    What is the network difficulty?

    The network difficulty is a number that gives an indication of how difficult it is to find a block. For Example, the Litecoin network automatically adjusts its difficulty every few days so that blocks are found on average every 2.5 minutes. This means that the more hashing power is on Litecoin, the harder it is to find a block.

    What is the share difficulty?

    The share difficulty is a number that gives an indication of how difficult it is to find a share. The lower this number, the more shares a miner will find at a given speed, and the lower their value. For this reason, the share difficulty does not affect miners’ expected earnings. Why does the pool report more shares than my miner? This pool serves variable-difficulty work units, so when you solve a share the pool counts it with multiplicity, according to its difficulty. For example, if you solve a share that is four times as difficult as the baseline share, it gets counted as four shares.

    Why variable-difficulty shares?

    The technique of adapting the difficulty to each miner’s hash rate allows the pool to measure workers’ speed more precisely while keeping bandwidth usage optimal. How does share difficulty influence my earnings? Short answer: it doesn’t. Long answer: a higher/lower share difficulty does not mean you will be earning more/less, because your expected earnings are independent of the share difficulty: they only depend on your hash rate and on the network difficulty. A higher share difficulty can only increase the variance, but not in a significant way.

    Is it possible to set the share difficulty manually?

    Yes, but it’s usually pointless, as the pool can automatically serve work of optimal difficulty. Some pools offer alternate ports for difficulty levels. Check with your pool for details.

    How is the value of a share (a.k.a. the PPS rate) computed?

    For example, again using Litecoin, the standard PPS formula is used: BS × R / ND × (SD / 65536), where BS is the block subsidy (currently 50 LTC), R is the PPS ratio (currently 1.25), ND is the network difficulty, and SD is the share difficulty (expressed as a multiple of the minimum share difficulty, which is what cgminer displays).

    What is a PPS ratio?

    A PPS ratio of 1 (or 100%) corresponds to the expected earnings of a Litecoin solo miner in an ideal world, without taking into account aspects such as orphaned blocks. (In practice, a Litecoin solo miner will always achieve a slightly lower ratio in the long run.) We say “expected” earnings because mining is a stochastic (random) process, and it is therefore impossible to know beforehand exactly how much a miner will earn in a given lapse of time. Thanks to merged mining, a technique that allows multiple cryptocurrencies to be mined simultaneously, it is possible to achieve PPS ratios higher than 100%. This is unrelated to what profit-switching pools do, as in merged mining all chains are mined at the same time. For this reason, merged mining does not cause sudden difficulty spikes and does not harm any of the involved networks.

    How and when does the PPS ratio change?

    The PPS ratio depends on factors such as the current network difficulty and market price of merged-mined cryptocurrencies. Since these elements can be highly volatile, the ratio can change frequently.
    Do block finders get extra reward in PPS pools?

    No. That would go against one of the main goals of the PPS system, which is to minimize variance. It would also make miners who don’t find blocks earn less, as the PPS rate would need to be adjusted downwards. Some do list recently found blocks and their finders, but only for transparency purposes.

    I’ve just started mining and all my shares are being rejected, what’s wrong?

    Make sure that your hardware and software support scrypt mining, and that they are configured correctly. Configuring a GPU for Litecoin mining requires particular attention; please refer to our configuration wizard to get an idea of what settings you need.

    Why doesn’t the hash rate reported by the pool match that reported by my miner?

    Because of how pooled mining works, the pool has no way of knowing your exact hash rate, so it can only estimate it based on how frequently you submit shares. After you start mining, it takes about 10 minutes for the estimates to become accurate. They will never be very precise, though; even if your miner’s hash rate is steady, the pool estimate will keep fluctuating around the actual speed.

    The pool keeps reporting a much lower hash rate than cgminer. What’s going on?

    If the estimate displayed on the site stays too low for more than 10 minutes, then you are almost certainly experiencing hardware errors. cgminer checks every solution generated by your hardware devices, and if one turns out to be incorrect because of hardware errors it (rightfully) doesn’t even submit it. Since pools can only estimate your hash rate based on how many solutions you submit in a given amount of time, their estimate will be lower than your real raw hashrate. This raw hashrate, which is correctly displayed by cgminer, is, however, not meaningful if the solutions your card generates are wrong. You need to make sure that all (not just the top one) of the HW figures in cgminer are zero or next-to-zero; if that’s not the case, you need to review your settings. Make sure you carefully read the documentation about scrypt mining provided with cgminer.

    What are stale shares?

    Servers provide each miner with some unique data that the miner must use to find a share. This data needs to be updated every time a new block appears on the Litecoin network, and that’s why servers must promptly notify miners when they detect a new block. Every second you keep on mining for the old block is wasted, because that block has already been found. If a new block is found before a submitted share hits the server, the share is marked as “stale”, and yields no reward. Stale shares are caused by latency, which can happen at various levels. The most obvious cause is a high ping time to the server, which however shouldn’t affect the stale rate by more than 0.5%.

    I’m getting more than 2% of stale shares, is this normal?

    No. On our Stratum servers, most miners achieve a stale rate well below 1%. If you’re GPU mining, make sure the intensity parameter is not set too high on your miners. More generally, consider that anything that pushes your hardware too much can cause additional latency, which results in a higher rate of stale shares. Some software latency is sometimes unavoidable when GPU mining, but if your stale rate is above 2% then something probably needs to be fixed. Should I set the –no-submit-stale option in cgminer? The –no-submit-stale option tells cgminer to skip the submission of shares that it detects as stale. You should only set it after you have made sure that your other settings, such as intensity, aren’t causing too much latency locally. Note that some of your submitted shares will still turn stale because of network latency, which is unavoidable.

    What is Stratum?

    Stratum is a network protocol for pooled mining, designed as a replacement for the now obsolete “getwork” protocol. It was originally proposed by Marek Palatinus (aka Slush), who also wrote a proxy for miners that could only understand the getwork protocol. Today most mining software supports the Stratum protocol natively, but the Stratum proxy is still useful for reducing network bandwidth usage on large installations.

    What is the “resume” extension to Stratum?

    It is an extension to the original Stratum mining protocol, jointly designed by Slush and ckolivas, the maintainer of cgminer. If your mining pool supports the extension and your Internet connection has a hiccup, the server may still accept any shares that your miners found while disconnected, if they reconnect and submit them within a reasonable time. As simple as this may sound, it is actually tricky to implement this feature correctly, because Stratum is not a stateless protocol.

  • I am able to mine and can see my account on the pimp farm. But I am confused about pool mining. where do I input my wallet address for my payouts. And is this address the same one given by a wallet like Jaxx?

  • Staff

    @chrismaranjes said in When I mine to a pool, how does the pool calculate my hashrate or my payout?:

    I am able to mine and can see my account on the pimp farm. But I am confused about pool mining. where do I input my wallet address for my payouts. And is this address the same one given by a wallet like Jaxx?

    Great question chris, and thanks!

    By default, PIMP OS will use known-good "safe" configuration example that you can customize with your own needs. Check out how to edit your config files here: https://forum.getpimp.org/topic/24/editing-the-miner-confs and then check out some of the other great guides in the Getting Started section.

    Also, the simplified quickstart is given to you when you type the newpimp command or click the Newpimp icon on the PIMP GUI Desktop.

  • @chrismaranjes Just as a random piece of advice, do NOT use the Jaxx wallet to send your mining rewards. If you look right on their site it tells you specifically not to. I was unaware of this and had 15 ZEC locked in a Jaxx wallet for almost a month before I could extract it.

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