Topic: are there speed-differences between Pools? (Read 3694 times)

This is kind of moot because optimally you do it with as many pools as possible. You distribute your hashing power among all available pools, and whenever you find a block in one you direct all hashrate to it. In AoBPMRS I only analyzed the case that all pools have the same hashrate, but I have reasons to believe that you need to distribute your hashrate in proportion to each pool's size.

Huh?  You are only withholding YOUR found block which occurs at the same rate regardless of the pool's relative size.  Yes if you hold a share too long it will go stale but the same event which causes it to go stale in a small pool will cause it to go stale in all pools.

The goal if I am understanding this correctly would be to
1) mine at a pool using a fraction of total hashing power
2) find a share (thus this pool will payout and any share you add that increases your % of payout is a net +)
3) direct all hashing power to that pool.
4) withhold the share for some period of time.*
5) increase the number of shares as a % of the pool share count to get a bigger cut of the reward then submit share.

* Yes in step #4 there is a risk of losing everything.  The risk of your share going stale is ~1.6% every 10 seconds.  Thus to be profitable you would need to increase your reward by >1.6% (relative to fair mining) in 10 seconds.  

So the question becomes is it easier to do that in a small pool, a large pool, or the size of the pool doesn't matter.

While a large pool has a shorter round (in time) it has the same length round (in shares).  

if you "lie in wait" until after a longpoll you have a stale share - useless

small pools larger variance...long round , more longpolls between block finds

big pools quicker rounds less longpolls between blockfinds

Interesting.  Also I don't envy you.  I got frustrated wading through those pages of false claims, long since debunked myths and poor logic (rigs don't have monitors so changing pools would be difficult?  I guess they never heard of pool hopping ).

I had always know about the witholding attack.  Never considered the "lie in wait".  One thing I am confused about if I read right you said it would be best to attempt this on a large pool?  Wouldn't it be best to attempt it on a small pool.  Point a fraction of hashing power at a pool.  When you get the share point all the rest of your hashing power at the pool (should be a sizeable multiple).  Given you have a small window the smaller the pool relative to your hashing power the more shares (and a % of pool) you can pump in.  Right?

If 10% of the reward is subject to full solo variance, it means the total variance is about (10%)^2 = 1% of solo variance, which is a lot. Let's say you have 500 MH/s, then it will be like mining for a normal pool with 50 GH/s. If you've mined in such a pool lately you know that its variance leaves a lot to be desired, especially for someone who went with PPS because he wants no variance.

With the protocol modification I proposed here. This is also discussed in subsection "6.2.3 Proposed solution - Oblivious shares" of AoBPMRS.

It wouldn't greatly increase the reward variance.  Even w/ 10% finder's fee only 10% of the reward is subject to variance.  What is your definition of "greatly"?


Of course a pool could delay broadcasting their own block by a fraction of a second.  Long enough to send out the validation check for blocks they solve.  This is the simplest but only allows a pool to check their own blocks.  If pools were concerned enough they could even privately share block solutions prior to public broadcasting.  

1) Pool X solves a block (x)
2) It broadcasts this to pools it shares data with (either for a fee or for as a "common defense" approach)
3) Pool A, B, C send data for block x to some % of their pool members (who at this point are unaware that block x is a known solution)
4) Pool X broadcasts block x to the public network a second later.
5) Miners which fail to solve block x are flagged.  Enough flags results in confiscation.

Not saying it is necessary.  Obviously there is an opportunity cost.  If the cost due to block withholding fraud is low (say 0.5% of gross revenue) then it wouldn't make sense paying 2% of gross revenue to defeat it.   Just as the proof of work doesn't prevent a 51% attack it simply makes it uneconomical a combination of a finder fee and block verification can make any such attack uneconomical.  The point of mentioning the 120 block window is to indicate a pool has multiple chances to catch an attacker and thus multiple chances to seize all funds (resulting in a 100% economic loss for the attacker).

This is a terrible way. It greatly increases the reward variance for miners thus defeating the purpose of the pool. An attacker who is bent on destroying a pool will not be fazed by a 1% reduction.

The best way to solve block withholding is oblivious shares.

This can work but it's sort of a band-aid solution, there are many potential problems.

The payments are delayed, but broadcasting the block to the network is not.

A block finder's fee is best way to solve issue of share withholding (give 1% to 10% of block value to the miner who finds it).  It can be combined with a validation check.  When a block is found, randomly send that data is a subset of the pool (don't do entire pool otherwise that is detectable).  It payments are delayed 120 blocks this means that an attacker would need to detected and properly respond to multiple validation attempts.

To improve moral any cheaters funds are seized and distributed to the rest of the pool members.  If pool takes no cut in this compensation honest miners may even see it as a benefit.

A share withholding attack is used against a PPS pool. If I modify my miner to send difficulty 1 shares to the pool, but not to send full difficulty block solutions, I still get paid the same amount per submitted share. Assume now that I and my fellow attackers are 50% of the pool's hashrate: the pool is earning 50% less in block generations than expected for the number of submitted shares, but still paying the same calculated rate per share, which will put them into financial losses quickly. The attack motive is purely lulz, or to bankrupt a competitor. This is hard to defend against; you can't just go banning miners that have never found a block, many have made over 400BTC pool mining but never found a block themselves. With PPLNS however, miners will be denying themselves earnings by not submitting the winning share they found, so it is not a realistic attack vector.

To address the original post, the factors that are the pool equivalent of "speed" in that they affecting earnings:
1. Efficiency/stale share rate
2. Uptime/responsiveness
3. Fees
4. Payment system (must not be proportional or "hoppable" system where earnings are reduced for other miners by bad actors)

I had the same experience, stales on btcguild were extremely low though.

All my mining rigs slows down if I connect to BTCGuild. I have no idea why that happens.

I'm mining at EclipseMC now. Best pool out there! 

I'm using CGMiner 2.0.8, Ubuntu 11.04 64 bits, Catalyst 11.6 and SDK v2.4.

Cheers,
Thiago

I didn't know eclipsemc.com was using merged mining already.  That's good to know!


I fully agree that we don't want "pool police" and that pools should simply outline their reward system to attract miners.  However, SMPPS was originally pushed as a way of eliminating the essential problem with 0% PPS mining where, in fact, all that changed was that the risk was transferred from the pool operator onto the miners.

I have no problem with pool operators using the proportional reward system but do have a problem if they suggest that the system is, in any way, fair to 24/7 or random-intermittent miners.

What could be more honest than "10% PPS where each share is difficulty 1 and is worth x BTC".  It may not be very lucrative compared to other options but it's about as simple and clear as you can get when it comes to reward systems.

The gambler is only "ruined" because each loss builds upon the next and ultimately the gambler ends up with all his assets in a single bet.  Given enough bets he will eventually lose that final bet.

Nobody is saying that a SMPPS pool can't fail.  What matters is HOW MUCH WILL THE AVERAGE MINER LOSE WHEN THE POOL FINALLY DOES PAY.

Lets say I am only given two options for mining:
a) PPS w/ 10% fee (guaranteed never to fail as it is contractually bound to payout from a reserve and shutdown before defaulting on any shares)
b) SMPPS pool w/ 0% fee.

The SMPPS pool although having a risk of failure and the PPS have 0% risk of failure (in this highly unlikely comparison) the SMPPS pool is still better if the miner loses <10% of lifetime shares when the pool fails.

The argument that a SMPPS pool "can" fail is a strawman.  Any pool can fail even for reasons unrelated to payout system.  It can be hacked, attacked, robbed, victim of internal sabotage, or outright theft by owner.




Hardly.  I would say collecting a 10% fee which is significantly outsized compared to the risk is more "dishonest".  If an operator made a guarantee that SMPPS pool can't fail that is one thing but none have done that. 

There is risk in everything.  The question is the expected loss going to be higher than alternatives and if so does the reduced variance warrant that risk.  We don't need any "pool police".  Miners can decide for themselves what they want.

Assumming equally good server, bandwidth, and management there are essentially three variables to a pool
1) cost - pool fees plus witheld transaction fees
2) variability - how consistent are payouts
3) risk - how much and how likely could the miner lose earned but unpaid income

Nobody can say which method is best because individuals desires are different.  Obviously those paying 10% PPS put 2 & 3 very high and put #1 very low.  Personally I think that is insane.  There is no variability because you are getting the worst case scenario, a 10% loss on every single share over your lifetime.  However obviously for some miners in their "analysis" nothing else matter.

Use a pool with a hopping-proof reward system and merged mining, such as eclipsemc.com and yourbtc.net .

The point is to use a hopping-proof method, where profits depends not on the pool's luck in the past, but in the future (which cannot be predicted without being a prophet).

That's a very restricted definition of pool-hopping.

The point with gambler's ruin is that the gambler is eventually ruined even if there is no house advantage.


It looks like people are completely missing the point about what's wrong with SMPPS. To everyone who speaks about how profitable it was for them to mine in SMPPS when the buffer was positive / mildly negative - congratulations, you have successfully hopped the pool! Hopping is mining only when it is attractive. Of course mining in SMPPS when the buffer is positive is attractive. It's entirely possible that, after the successful start, you'll be able to keep mining well into a negative buffer before you hop away, and have an overall profitable period. You'd make even more profits if you optimized your hopping using proportional pools.

But the question isn't really what you will feel when the buffer reaches -10,000 BTC. It's about others who would consider joining the pool at that point. It would be silly of them to join this over other pools because the maturity time will be insanely high. And those who previously mined will also quit. And the pool will collapse. And that this is inevitable is built-into the design of the pool. I don't know when this will happen as this is random. It could be quickly and it could take decades.

Operators are dishonest if they offer a method which could collapse any minute. People who mine there now when everything's peachy with the intention to leave when things get rough, are plain hoppers which as I commented elsewhere I think is unethical. And those who keep mining even during a highly negative buffer are simply working against their own best interests.

And, as teukon implied - if SMPPS is safe it means that PPS can be offered with a low fee. And this is even more so if the operator makes a calculated risk assessment, raises the capital needed to have a sufficient buffer, and acts as a proxy to a larger pool such as p2pool.

So what are your suggestions where I can earn most stable and also lowest fees finally most BTC/Day? Maybe with merged mining?

There is no house advantage in Bitcoin mining (well unless you are a high fee pool operator). 


Many people did.

I likely wouldn't join but if I had a sufficient reserve it would be a calculated risk to keep mining.  Of course nominal terms are silly.  What matters is buffer relative to expected value over some time. 

So say 5 days negative buffer or a 30 days negative buffer.  If the buffer got sufficiently negative then the pool "could" collapse but as we see later this doesn't really matter.


No you won't.  The 1000 BTC would still be owed to the miners not the pool owner. You would make nothing out of nothing.


No they won't.  It is highly improbable that any SMPPS failure would cost miners more than 10% of lifetime revenue which is what a 10% PPS pool does.

Simply put miners using a 10% PPS pool are GUARANTEED to lose 10% while miners of a SMPPS pool have a small chance of losing some % of their revenue but likely much less than 10% unless the have >10% of their LIFETIME shares in the buffer.  As time goes on the likelihood that a miner could lose >10% becomes more remote.

This isn't to say there is no risk simply that the risk isn't extreme and the amount of potential loss can be managed.

I mined on Ars for about ~9 months.  The most I ever had in buffer (thus my max loss) was 5 days worth of owed shares.  Even if the pool went bankrupt right then, then most I would at most have lost 2.2%.  Effectively my loss would be a 2.2% fee which is pretty damn good for no variance revenue. 

If you can understand the problem with running a 0% fee PPS pool (assuming your costs are covered) then, with some thought, you will see the similar problem with SMPPS.  If you don't see a problem with this then look up "playing the Martingale" for a foolproof way of gambling and beating the casinos.

If you don't see the relationship then:
Would you mine at the SMPPS if the buffer was 500 BTC in the red?
What if it was 10`000 BTC in the red?

What would happen if people started leaving the pool en masse when the buffer is negative (thinking that if the pool recovers they'll get their due reward anyway)?  Would you continue to mine there yourself?

If SMPPS pools will always recover then how about starting a SMPPS pool with a negative buffer of 1000 BTC.  If you are right and SMPPS is sound then the buffer will eventually hit 0 and you will have made 1000 BTC out of nothing!  Go for it!

Just as with simple pyramid schemes, SMPPS might look good at first but, if it goes on long enough, a lot of miners will lose is a big way.

Yes, beware of this.  It seems many of the small pools have no plan of action for when their pool dies.  In many cases, submitting a share is gambling that the pool will last sufficiently long.  For bigger pools or PPS pools this is not an issue.

Pool hopping isn't the issue.  Inequitable share of the revenue is.  Some pools are far more equitable than others.  Some pools may it trivial to grab an inequitable share.

If someone can get an inequitable share then they will.  Given mining is a zero sum game if someone is getting more than "full PPS*" then someone else is getting less.


Full PPS = (block reward + fees)/(Difficulty)

The goal should be to select a pool which makes it as difficult as possible for someone else to gain more than "full PPS".  Proportional pools are the absolute worse on that metric.