What are Bitcoin Mining Pools?

Mining Pools是什么？
Last updated 10th March 2014

One of the first questions that anyone interested in mining cryptocurrencies faces is whether to mine solo or join a ‘pool’.
There are a multitude of reasons both for and against mining pools.
However, if the hash rate distribution across the bitcoin network is anything to go by (and it is) then most miners are opting to join a pool.
Here’s what you need to know.
有兴趣挖矿的人第一个要考虑的问题就是：打算独自挖还是加入pool挖。支持和反对pool的原因都有很多。
按照bitcoin network目前的hash率分布来看的话，大多数miners都选择了加入pool。这个我们下边说。
Pros and cons
正面和反面
If you’re deciding whether to join a mining pool or not, it can be helpful to think of it like a lottery syndicate –
the pros and cons are exactly the same.
Going solo means you won’t have to share the reward, but your odds of getting a reward are significantly decreased.
Although a pool has a much larger chance of solving a block and winning the reward,
that reward will be split between all the pool members.

Therefore, joining a pool creates a steady stream of income,
even if each payment is modest compared to the full block reward (which currently stands at 25 XBTC).

It is important to note that it is important for a mining pool to not exceed over 51% of the hashing power of the network. If a single entity ends up controlling more than 50% of a cryptocurrency network’s computing power, it could – theoretically – wreak havoc on the whole network. In early 2014, many voiced concerns that the GHash.io bitcoin mining pool was approaching this threshold, and miners were urged to leave the pool.
如果你还在考虑是否加入pool，可以把pool当做一个彩票机构，正反两面都是一样的。
单干意味着你自己分享你的reward,但是你获得reward的几率会明显下降。虽然pool爆块的几率大得多，但是相应的reward也要被拆分后分给pool的所有成员。
尽管如此，加入pool还是会有个稳定的收益，虽然收益相比自己爆块的reward少得多(目前是25BTC)。
It is important to note that it is important for a mining pool to not exceed over 51% of the hashing power of the network.
If a single entity ends up controlling more than 50% of a cryptocurrency network’s computing power,
it could – theoretically – wreak havoc on the whole network.
In early 2014, many voiced concerns that the GHash.io bitcoin mining pool was approaching this threshold,
and miners were urged to leave the pool.
需要密切注意的是：pool的hash算力决不能超过全网的51%。如果有pool算力超过了50%，那它理论上就控制了整个网络。
2014年初，需要人很关切GHash.io因为它的算力已经接近阀值，所以敦促miner离开这个pool.
Currency difficulty

In bitcoin’s case, the current difficulty level is so high that it’s
practically impossible for soloists to make a profit mining. Unless, of course,
you happen to have a garage full of ASICs sitting in Arctic conditions. If
you’re a beginner, joining a mining pool is a great way to reap a small reward
over a short period of time. Indeed, pools are a way to encourage small-scale
miners to stay involved.


What to mine?
从BTC目前情况看，当前的难度系数太高了，导致单干基本不可能获利。除非你正好在机房有很多矿机（ASIC）。
如果你是个新手，加入pool是个不错的选择，至少可以在短期获得小额利润。事实上，pool也是鼓励小户miner加入的一种方式。
Of course, bitcoin is not the only currency out there –
it’s easy to find lists of mining pools for your chosen cryptocurrency.
BTC也不是挖的唯一币种，很容易找到很多挖其他币种的pools.
One method of mining that bitcoin facilitates is “merged mining”.
This is where blocks solved for bitcoin can be used for other currencies that use the same proof of work algorithm (for example, namecoin and devcoin).
A useful analogy for merged mining is to think of it like entering the same set of numbers into several lotteries.
有种挖矿方式称为“merged mining”. 它的意思爆块时，爆的block除了在BTC网络用，还可以在其他币种上用（例如namecoin and devcoin）。
First-time miners who lack particularly powerful hardware should look at altcoins over bitcoin –
especially currencies based on the scrypt algorithm rather than SHA256.
This is because the difficulty of bitcoin calculations is far too high for the processors found in regular PCs.
刚起步的miner如果缺乏强悍的硬件，可以关注下其他币种，尤其是基于scrypt算法的，而不是SHA256的。
If you’re not sure which currency to mine, there is a pool called ‘Multipool’
which will automatically switch your mining hardware between the most profitable altcoin.
Multipool updates every 30 minutes, and over time you’ll see balance grow in multiple altcurrencies.
If required, the pool does allow you to fix your hardware on just one altcurrency too.
如果你不知道挖哪种币好，有个‘Multipool’可供参考。它会自动切换到最赚钱的币种上。Multipool每30分钟刷一次，慢慢地你会看到你的账户在多个币种上都有收入。
如果需要，你也可以固定设置挖某一种币。
However, Mark from nut2pools.com said of this type of switching pool:
“Loyal coin followers hate them because as soon as the difficulty of a coin drops, the profitability of it rises.
Then all the multipools swing round, push the difficulty through the roof in a few hours, then leave again.
It leaves the loyal coin followers having to mine the difficulty back down again at very low profitability.”
然而nut2pools.com 的Mark说了他对这种自动切换的pool的看法：忠实的粉丝很憎恶这种类型的pool，因为币的难度系数一降低，盈利能力就上升。
而multipools在多币种间来回切换，可以几小时内把某币种的难度系数推高，然后就离开了。剩下的残局需要其他miner重新把难度系数重新挖回低水平。
Pool rewards

When deciding which mining pool to join, you need to weigh up how each pool shares out its payments
and what fees (if any) it deducts.
考虑加入哪个pool是你要权衡pool的分成方式和手续费。
There are many schemes by which pools can divide payments.
Most of which concentrate of the amount of ‘shares’ which a miner has submitted to the pool as ‘proof of work’.
pool的分成方式有很多种，大多是基于miner贡献的‘shares’量来决定的。
Shares are a tricky concept to grasp. Keep two things in mind: firstly,
mining is a process of solving cryptographic puzzles; secondly, mining has a difficulty level.
When a miner ‘solves a block’ there is a corresponding difficulty level for the solution.
Think of it as a measure of quality.
If the difficulty rating of the miner’s solution is above the difficulty level of the entire currency,
it is added to that currency’s block chain and coins are rewarded.
Shares是个比较难理解的概念。？？？？？
记住两件事：
1:挖矿是个解决加密难题的过程；
2：挖矿有难度系数。
如果miner爆块了，爆的块也有个对应的难度系数。
可以把这看做一个质检方式:
如果miner提供块的难度系数高于全网的难度系数，爆的块会被加入到block chain,然后会获得相应reward.
Additionally, a mining pool sets a difficulty level between 1 and the currency’s difficulty.
If a miner returns a block which scores a difficulty level between the pool’s difficulty level
and the currency’s difficulty level, the block is recorded as a ‘share’.
There is no use whatsoever for these share blocks,
but they are recorded as proof of work to show that miners are trying to solve blocks.
They also indicate how much processing power they are contributing to the pool – the better the hardware,
the more shares are generated.
此外，pool设定的难度系数介于1和全网难度系数。
如故宫miner返回的block中存储的难度系数介于pool的难度系数和全网的难度系数，这个block会被记录为‘share’.
虽然这些‘share’没有任何用，但是可以作为miner的POW，表明miner也尽力挖矿了。
‘share’也可以标示miner的算力贡献量-硬件越好，‘share’贡献越多。
The most basic version of dividing payments this way is the ‘pay per share’ (PPS) model.
Variations on this puts limits on the rate paid per share; for example, equalised shared maximum pay per share (ESMPPS),
or shared maximum pay per share (SMPPS).
Pools may or may not prioritise payments for how recently miners have submitted shares:
for example, recent shared maximum pay per share (RSMPPS). More examples can be found on the bitcoin wiki.
最基本的分成方式是PPS模式。还有很多PPS模式的变种方案：区别在每个share的付款比例；
例如ESMPPS：根据share贡献平均分配方案。
还有SMPPS。？？？？
pool可能无法根据miner提交share的频率(间隔时间)来设定优先级。
例如RSMPPS模式。更多分成方式参见wiki.

The other factor to consider is how much the pool will deduct from your mining payments.
Typical values range from 1% to 10%. However, some pools do not deduct anything.
决策加入哪个pool的另一个因素就是pool的手续费。典型的从1%到10%不等，也有些pool不收手续费。

Starting to mine with a pool

Having decided which currency to mine and which pool you’ll work for, it’s time to get started.
定好挖哪种币和加入哪个pool就可以开始挖矿了。
You need to create an account on the pool’s website, which is just like signing up for any other web service.
Once you have an account, you’ll need to create a ‘worker’.
You can create multiple workers for each piece of mining hardware you’ll use.
The default settings on most pools are for workers to be assigned a number as their name,
and ‘x’ as their password, but you can change these to whatever you like.
你需要在pool的站点先注册个账户，和在其他站点一样。
有了账户后，你需要创建个worker.你也可以为你的每个机器都创建个worker.
大多的pool的默认设置会给新建的worker设置个数字作为name,x作为密码，但是你可以修改这些值。