It almost looks like you lost connection. Judging by the leftovers of 18014 - looks like it probably happened about 30min before the end. And you stayed disconnected through the next two rounds (which were rather short ones - 10 and 36min) and then reconnected. For at least the last hour of 18017 you did have connection.
Disconnect? дa чтo yгoднo - miners submitted shares whole time. Meня этo нe вoлнyeт - just curiosity more than another thing.
Don't get me wrong - I have no interest in providing you with misleading information (and for the record - neither a good one).
However, I didn't say it just because that's the way I like it - I was merely making an observation based on the facts (the btc awards that you got for each of those rounds).
A few questions for you - how do you know that your miners did actually work?
Knowing miners mining because of watching monitors and seeing cgminer going without errors. Setting zero on display command when block change and watching accepting blocks count up. It can be mystery without solution forever from this day to me. Thank you.
I don't know cgminer well enough to tell you if "cgminer reporting submitted shares" actually means that the shares did indeed get submitted. Although it probably does.
I was rather trying to hint that it is possible that during this time your miner may have gotten disconnected (without you noticing), then got reconnected and continued to submit shares (at which point you may have seen it working fine). However you wouldn't know about that hour or two when it was trying to reconnect and didn't submit any shares. That's unless you were actually watching cgminer's performance during those two rounds - between 2013-05-13 20:21:17 and 21:07:59 server time.
It is also possible that Amazon's balancer moved the end node to which you were connected, and your computer or router had cached the IP or DNS data, and took some time to learn about the new IP and reconnect. I caught this exact case in the act - see
https://bitcointalksearch.org/topic/m.2108291 - my miners lost connection and sat idle for a while without me noticing it immediately.
As for if we'll ever know for sure - I think you're right. We may never learn for sure what exactly happened.
We should rather take the lessons learned and start more logging, so that when it happens the next time we have a better idea of what might have gone wrong.
I can say I totally believe. I had same problems and given up on the pool. I was looking at logs of cgminer showing noting wrong but shares were missing.
Log looks like that:
[2013-05-14 08:13:33] Accepted 9c18e33e Diff 1/1 GPU 2 pool 0
[2013-05-14 08:13:35] Accepted efb855a5 Diff 1/1 GPU 2 pool 0
[2013-05-14 08:13:36] Accepted 2d4f916a Diff 5/1 GPU 1 pool 0
[2013-05-14 08:13:37] Accepted 854c4a6c Diff 1/1 GPU 2 pool 0
[2013-05-14 08:13:40] Accepted 17474462 Diff 10/1 GPU 2 pool 0
[2013-05-14 08:13:52] Stratum from pool 0 detected new block
[2013-05-14 08:13:54] Accepted b0de7eea Diff 1/1 GPU 3 pool 0
[2013-05-14 08:13:55] Accepted 6c49452a Diff 2/1 GPU 0 pool 0
[2013-05-14 08:13:57] Accepted 6e920082 Diff 2/1 GPU 2 pool 0
[2013-05-14 08:14:03] Accepted d448d5c4 Diff 1/1 GPU 3 pool 0
[2013-05-14 08:14:07] Accepted c45369d9 Diff 1/1 GPU 2 pool 0
So seeing
[2013-05-14 08:13:52] Stratum from pool 0 detected new block
means that you got data about new block and stratum sends data to you.
[2013-05-14 08:13:55] Accepted 6c49452a Diff 2/1 GPU 0 pool 0
This means that pool accepted the share. It also means that startum is sending you work since you have only about 1 minute buffer.
I had all this in logs so pool did communicate and rsbriggs also saw this on screen. So it is time to accept that pool has issues and there is no Slush to fix them. Now I hope he is only on holidays but I'm afraid for some time that that is not the case and that something happen to him.
EDIT: I didn't have any disconnections like you. Just missing shares
EDIT2: Interesting thing. We had 5 minutes downtime with my primary pool. One miner jumped to Slush the other detected it as not working and didn't connect to stratum, stratum2, stratum3 or api and concted to my old backup pool. They are on same line with same network settings and it happened in about the same time that rsbriggs reports the problem. Guess load balancers???