Not exactly. The experiment with gigaminer was small (about a million shares), but a complete disaster. We ended up paying our miners for about 200,000 valid shares which have been rejected upstream.

ABC miners are always credited for every valid share they submit as long as it’s not a duplicate. Even if an 'upstream pool' later turns out to reject the share, the original miner is still credited.

That's another way that we create a predictable experience for our miners, which cost us quite a bit in this instance.

You are hitting the nail on the head despoiler. Although we tested successfully under light load, the switch did not go altogether smoothly when it was rolled out in full. Those issues have been resolved last night. We will report on the DDOS and the countermeasures shortly.

Hi everyone,

Thanks for your patience. While we took care of rolling out the DDOS countermeasures, a lively discussion has been going on in the ABC thread. We think the time has come to explain a few things about how ABCPool works behind the scenes.

Well-respected forum member Meni Rosenfeld ran the numbers on running a PPS pool, and while ABCPool was still young he shared those with us in a PM conversation:
Well, as you might imagine, we did not have 10,000 BTC. Neither did at least three other PPS pools that have since gone out of business or changed their reward model.

But if we could somehow decrease that enormous risk, the required buffer could also be a lot smaller. That’s why we now do what most miners do. They consider solo mining too risky, and aggregate their mining power with the mining power of others by joining a pool. Or in our case, joining several pools.

And as any pool miner has experienced, the result is as expected: less variation in the payouts we receive. In turn we are now able to pay the ABC miners their PPS rewards without a 10,000 BTC buffer, without a 10% fee, and without the immediate loom of pool bankruptcy hanging over us.

Pool growth in December was overwhelming. Meanwhile we were still compensating (1) orphaned blocks and (2) stale shares. And although the risk was reduced by pool mining, we had (3) a lot of bad luck that month. That's when we had to start charging the 4% fee.

We understand that there might be people who want to leave ABCPool, having heard this news. Maybe you want the pool operator to take the full risk of finding blocks. Maybe you'd rather take your chances on a non-PPS pool, now that you know that we do so too. Maybe you feel that we should have disclosed this information earlier. Whatever your reason, that's fine with us. Of course if you stay, you can continue to enjoy all the benefits ABCPool provides; nothing is changing there.

We hope this explanation clears things up a bit. You are free to ask any question you have about the pool's workings. We will however not go into too much detail because the competition is always watching.



There were a few comments in this thread recently that are inviting a reply:
We may list block history and top hashers in the future. There are no rounds however because we pay per share, not per round. See also https://bitcointalk.org/index.php?topic=33586.msg685134#msg685134


Some of ABCPool hashpower went to Goat’s project, around a million shares.

The DDOS is indeed a completely separate incident, involving thousands of hosts. Goat had nothing to do with it. Now that the countermeasures are in place, we will supply a post-mortem on the DDOS shortly.

Happy hashing everyone!
MC & Chlorine

We have read your comments and will respond later today. For now rest assured that your shares will always be rewarded as agreed, just as they have been in the past.

There's some other news: one of the stats tables became corrupted. We've since restored it from yesterday's backup. on your stats page you will not see any shares reported between 18:51 (yesterday) and 02:57 (today) UTC.

The issue has only affected the statistics as displayed: All shares from that period have been credited to your balance at the normal PPS rate.

We're currently migrating ABCPool to a load-balanced setup, which is causing some unforeseen connectivity issues. We hope to have it resolved within an hour.

You have probably noticed ABCPool was down for more than a day last week due to a DDOS attack. While we have been working around the clock to mitigate it, it's near impossible to continue service during such attacks. Several large pools have shown that in the past (deepbit, slush, btc guild to name a few). Still, we are working hard on a number of countermeasures for the future that will at least be effective in some scenarios.

We are sorry for any downtime the attack has caused you.

For your mining pleasure we have lowered the nominal fee to 1.5% for the rest of January!

Happy hashing!
MC

FYI: Asdf2121's issue was handled by Chlorine on 2012-01-19.

Service levels are indeed back to normal since a few hours. Don't start celebrating yet, we still need to finish up the work on hardening the pool against these kind of events.

MC

The barrage has not subsided yet, and I'm afraid a workaround is impossible at the moment.

Time for some sleep. We'll continue working on this first thing tomorrow, but it seems like we may just have to wait this one out.

Thanks jwu, we are aware (and still working on it). The attack had subsided for a bit, but is now back in full swing. It seems some more measures are necessary.

UPDATE: we have been experimenting with various ways of mitigating the attack. A portion of all users is now able to mine again, but network congestion from the attack could degrade performance. If you are experiencing dropped connections you are advised to use a backup pool for now.

If you cannot connect, it will probably be at least 8 hours before you can mine on ABCPool again.

Looking into it.

UPDATE: It's official, ABCPool is playing with the big boys now: We are being DDOS'ed! We're now going to do some emergency whitelisting on the network perimeter and then figure out a more permanent solution. The pool will most likely be unavailable for a few hours; keep an eye on the forum for updates.

Hi miners,
16:00 UTC: Problems at our hosting provider caused ABCPool to be offline for now. Cause is yet unknown, but i'm inclined to guess that the pool will be back online in half an hour.

Sorry for the inconvenience!

UPDATE 17:00 UTC: pool is back online. The bare metal on which the server was hosted gave up. Data is unaffected, all shares have been counted. Please check your miners to make sure they have reconnected.

Thanks for your patience while we resolved this. Happy hashing again everyone!

I've looked through our source code, and at some point we switched to shorter timeouts for the longpolls. They're now every 120 seconds, which means that that timeout is indeed what diablominer is reporting. Therefore what you see is expected behavior.

While the negative part of this effect will be between 0.00% and 0.02% in wasted GPU cycles (depending on your latency), the positive effect more than compensates that because of the faster longpoll-handling whenever a new block is reported.

As far as i'm aware there's no parameter to hide the message in Diablominer. Why don't you PM me the log output and I'll take a look at it. Please also include your GPU/worker configuration.

Hi 99Percent,
That error message indicates that the long poll connection was terminated. ABCPool releases those connections on purpose for performance reasons.

The message should occur ca. every 10 minutes, and only when a new block was not found within that time. In those cases it is innocent and you may ignore it. Diablominer will immediately reconnect after the connection has been released.

hope this helps,
MC

Kudos to BTCGuild for providing their block history to the mining community. And your interest is noted!

Chlorine and I are trying to do the best we can with our limited resources. The next feature to be introduced will most likely be automated password recovery and account reset, since the current manual process is slow and takes quite some effort to support as we keep gaining more and more users.

Of course, as always, you're welcome to suggest any other features you'd like to have on ABCPool! You can reply here or PM me or Chlorine directly. Just don't expect it to be implemented the next day!

Hi Stoppots,
Every member of ABCPool is paid per share. The share price is determined by a formula based on the theoretical expected number of blocks to be found. That reward is independent of when or how much blocks are actually found. As such we do not list the block history, sorry!

Hi Hotdog,
We have had a few minutes of connectivity issues this morning, reporting is running fine.

Ah! Maybe now I finally understand where the confusion is coming from. Thanks for sharing your reasoning! Now to clear things up, hopefully: In the Bitcoin world there is a difference between 'invalid shares' and 'invalid blocks'. At ABCPool we subdivide invalid shares into 'stale shares' and 'invalid shares':

• Stale share - a share (handed in by a miner) that is solution for the previous block. It's up to a few seconds late and therefore useless. ABCPool pays you anyway. Poolwide average is at 0.4% of total shares, but the individual number differs depending on your latency, software and hardware.
  
• Invalid share - a share (handed in by a miner) that is duplicate, wrong, or extremely late. ABCPool does not pay for these.
  
• Invalid block (or orphan block) - a valid share submission that is also a valid block solution, but later turns out to be rejected by the bitcoin network. The theoretical (50BTC/difficulty) reward formula assumes all blocks are valid. However, 1.5% of found blocks become orphan blocks that do not generate 50 BTC. This is because of network latency in the Bitcoin network and has nothing to do with the miners connection to the pool. However, that practical difference of 1.5% makes the theoretical reward unrealistic. At non-PPS pools orphan blocks also cost you 1.5%, even though a 0% fee is listed: The pool doesn't get the 50 BTC reward, so it is also never distributed among miners (there are exceptions, such as deepbit). At PPS pools, the 1.5% can only be compensated by a 'fee'.
  

I hope this explanation clears things up. I will also change the terminology from 'invalid block' to 'orphan block' to better highlight that it is very different from an 'invalid share'.

Indeed, low-quality miners benefit more from the stale-compensation than high-quality miners; the individual stale-rate might vary roughly between 0% and 1%. Our goal is to provide the most predictable mining experience out there. PPS is of course already the most predictable reward mechanism, but stale-compensation makes it even more predictable. When you consider non-pps pools, you'll always need to correct the fee to include the expected stale rate. Since other pools do not do that calculation for you, our 'effective fee' attempts to make the correction the other way around.
Excellent idea. I've added it to our features roadmap!