CPPSRB is a good system.
There's nothing wrong with CPPSRB itself, but if I add up all the shares in the block list
http://eligius.st/~wizkid057/newstats/blocks.php , I get a total of 29618979908 shares found, with total difficulty of 27904252293. This means average luck over the last 19 months (all of the stats) is only 94%. That seems awfully low to be just a case of bad luck over such a long period.
Any explanation ?
Not even sure what explanation you're looking for. Asking me to explain why we've had some bad luck is like asking me when exactly we'll find our next block... neither of which anyone is really capable of answering definitively.
We can speculate, however, and ff you're trying to say there is some underlying issue with the pool which "causes" bad luck, then you're welcome to go through the data yourself and try to find a cause. I've checked and double checked everything about the pool from top to bottom to make sure everything works as intended. I also regularly scan the shares database for any duplicate work submissions (which would indicate the pool giving useless duplicate work to miners) and find none. I also check the top miners for block withholding, statistically, and have never found anything outside of normal variance. Trust me, I'm pretty paranoid and I've gone over everything as much as possible.
The only issue the pool has ever had which would contribute to bad luck is the overwhelming amount of orphaned blocks that occurred back when the pool was running SMPPS (over a year ago). With our new server our orphan % has been very low. (1.5% over the past 3 months compared to 4% all time).
But, I think your math's result is mainly due to variance recently introduced by the recent leaps in network difficulty and the increase in the pool's overall hash rate over the past year, both add substantial variance to your broad all time difficulty_sum/accepted_sum stat. Those sums include 19 months of counts, but, over 50% of the shares accepted over all time by the pool have been accepted in just the past 40 days! 40 days is not enough time for variance to level out.
Here's some interesting data I came up with fiddling with the stats database just now:
- 50.51% of all accepted shares were accepted in the past 40 days. This would make any "long term" variance stats which includes recent data pretty irrelevant.
- From start of the pool to block 240000 overall pool luck was 99%. (5437253099.88402 difficulty / 5490920747 accepted shares). A good glipse at a period of time before the exponential rise in difficulty where the variance of our pool hash rate vs network difficulty would actually have had time sufficient time to level out, and it did as expected.
- The worst luck for a 60 day window was about 88%. The best was 111%.
- A miner who started mining at the pool on day one of CPPSRB and mined at the exact same hash rate since then will have been paid just over 98% PPS as an all time average.
Given time, the variance of the diffculty/accepted ratio will average out to be 100% minus % of orphans (
Law of Large Numbers). With the network difficulty rising sharply, it will probably take a while for this to happen, and until then we'll swing on either side of that variance, along with every other pool.
Since all pools are subject to variance, and most other pools have fees... you're still probably best off with Eligius. I'll be the first to say, pool operator or not, if I thought I could get more coins for my hash power elsewhere I wouldn't be
mining at Eligius myself.
-wk
Edit: fix some typos, add a couple of links