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Bitcoin => Mining => Topic started by: jh316 on March 24, 2011, 03:45:31 PM



Title: What kind of pool would be best for a 220 Mhash card?
Post by: jh316 on March 24, 2011, 03:45:31 PM
I'm running a 6870, it averages about 220 and peaks near 300.  There's share based and scoring and all this, what method would be best for mining overnight or when I'm in class, and what pools use that method?


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: dbitcoin on March 24, 2011, 04:00:34 PM
I'm running a 6870, it averages about 220 and peaks near 300.  There's share based and scoring and all this, what method would be best for mining overnight or when I'm in class, and what pools use that method?

In long term doesn't matter (select any), in short term probably pay per share.


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: [Tycho] on March 24, 2011, 04:13:22 PM
I'm running a 6870, it averages about 220 and peaks near 300.  There's share based and scoring and all this, what method would be best for mining overnight or when I'm in class, and what pools use that method?
Welcome to my pool @ http://deepbit.net
I would recommend PayPerShare method if you aren't mining 24/7


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: theGECK on March 24, 2011, 04:26:39 PM
Here's my analysis of the three types I know of:
Code:
Score-based
     - More resistant to "pool-hopping" techniques ("cheats")
     - More variation in short-term payout

Share-based
     - Same payout over time as score-based, but with more vulnerabilities to gaming the system
     - Allows people to jump in and out of a round with no penalty

Pay Per Share
     - Allows you to get guaranteed payout, but with a significant (10% is most common) fee.
     - I can't see a reason to do this over share based method.

If you're mining for short periods of time, I'd go with a share-based method because you don't know for sure when the block will be found, and you won't be continually dropping new shares into the round. This would preserve your share's values, and prevent the degradations that happens with a score based system. However, if you are going to be around for longer periods of time (5+ hours) I would recommend a score-based system because of the resistance to different techniques used to maximize payout which then deprives a share based pool of hash power.

I can't figure out what a pay per share would be good for, unless you have a really slow CPU and can't get any shares into the round before it ended and always had invalid shares.


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: Meni Rosenfeld on March 24, 2011, 04:34:45 PM
Pay per share is good if you want to be able to very easily verify that you're getting exactly what you're supposed to and not being cheated by the operator or other participants, so it's a good way to start out. But in a few days you'll outgrow it and want to maximize your earnings. At that point I recommend score-based over share-based. Score-based has some more variance, but higher expectation if cheaters are present (or the same expectation if there are no cheaters).

slush (http://mining.bitcoin.cz/) is the only one I know to use score-based. Hopefully at some point someone will implement my method (http://bitcointalk.org/index.php?topic=4787.0), which is not only cheat-proof but also has controllable variance.


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: dbitcoin on March 24, 2011, 04:54:01 PM
slush (http://mining.bitcoin.cz/) is the only one I know to use score-based. Hopefully at some point someone will implement my method (http://bitcointalk.org/index.php?topic=4787.0), which is not only cheat-proof but also has controllable variance.

Nope,  BTCMine (http://btcmine.com/) now 2 days as switched to score based payout model.


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: rasputin on March 24, 2011, 05:15:40 PM
Pay per share is good if you want to be able to very easily verify that you're getting exactly what you're supposed to and not being cheated by the operator or other participants, so it's a good way to start out. But in a few days you'll outgrow it and want to maximize your earnings. At that point I recommend score-based over share-based. Score-based has some more variance, but higher expectation if cheaters are present (or the same expectation if there are no cheaters).
A pay-per-share pool system is bound to pay out less than the other approaches, yes, as the pool operators need a margin to protect themselves from bad luck.

Quote
slush (http://mining.bitcoin.cz/) is the only one I know to use score-based. Hopefully at some point someone will implement my method (http://bitcointalk.org/index.php?topic=4787.0), which is not only cheat-proof but also has controllable variance.
Hmm.. Can't say I intuitively grasp the cheating approach. Once you leave a share based pool, your part of the payout shrinks as well -- but I recon slower than your profit from the pool you switched to?
Could you try quantify the loss from people using this technique? Is it likely to be larger than the 2% fee difference between slush's pool and bitcoinpool, which is free, for instance?


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: Meni Rosenfeld on March 24, 2011, 07:23:43 PM
Hmm.. Can't say I intuitively grasp the cheating approach. Once you leave a share based pool, your part of the payout shrinks as well -- but I recon slower than your profit from the pool you switched to?
Could you try quantify the loss from people using this technique? Is it likely to be larger than the 2% fee difference between slush's pool and bitcoinpool, which is free, for instance?
When you submit a share to a share-based pool, your expected payout from it depends on the number of shares already in the round and is much higher in the beginning of the round. Cheaters who are after a profit but have no interest in otherwise causing harm, will mine until the number of shares is 0.435*difficulty, and from that point mine solo or switch to another pool.
If it helps your intuition, think of this - if there are already 2*difficulty shares, then no matter what happens, any share you submit will give you less than 1/(2*difficulty) of the block. While if you mine solo, you have 1/difficulty chance to get a whole block.
In the limit where there is a nest of cheaters that supply 100% of the mining until the point of improfitability, the honest participants are left to split the rewards of rounds longer than that, which on average is 70% of solo mining payout. This is much worse than any fee, even the seemingly high ones for PPS.
This problem can be mitigated by making it hard to find out how many shares are in the current round. I don't know how effective this is.


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: xenon481 on March 24, 2011, 07:28:01 PM
Hmm.. Can't say I intuitively grasp the cheating approach. Once you leave a share based pool, your part of the payout shrinks as well -- but I recon slower than your profit from the pool you switched to?
Could you try quantify the loss from people using this technique? Is it likely to be larger than the 2% fee difference between slush's pool and bitcoinpool, which is free, for instance?
When you submit a share to a share-based pool, your expected payout from it depends on the number of shares already in the round and is much higher in the beginning of the round. Cheaters who are after a profit but have no interest in otherwise causing harm, will mine until the number of shares is 0.435*difficulty.
In the limit where there is a nest of cheaters that supply 100% of the mining until the point of improfitability, the honest participants are left to split the rewards of rounds longer than that, which on average is 70% of solo mining payout. This is much worse than any fee, even the seemingly high ones for PPS.

And some of the graphs that slush has posted show circumstantial evidence that such cheating by miners actually was going on in his pool before he changed to a Score based method.


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: jh316 on March 24, 2011, 10:16:34 PM
Can you explain what exactly the difference between scored and shared is?


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: nphard on March 25, 2011, 04:03:18 AM
Can you explain what exactly the difference between scored and shared is?

Here's a comprehensive post by slush about it: http://bitcointalk.org/index.php?topic=1976.msg50002#msg50002 (http://bitcointalk.org/index.php?topic=1976.msg50002#msg50002)


Title: Re: What kind of pool would be best for a 220 Mhash card?
Post by: Meni Rosenfeld on March 25, 2011, 07:34:05 AM
Can you explain what exactly the difference between scored and shared is?
In shared-based, all shares have the same weight (that is, portion of the block reward).
In score-based, recently submitted shares have more weight.