Neither one is the issue, is it? That mainly applies to RPis, as on a standard box, those things are just rounding errors.
That would imply that the problem is Chia software, and it really doesnāt look like, as otherwise more people would be banging on this issue.
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Kind of off topic, but since you started it.
You mean, you cache plot file results? Those HDs need to spin all the time, though.
Would it be possible to pre-parse those plots, and save results somewhere (not on those drives), and just run from those pre-parsed files? I mean, during those 5s lookups. Wouldnāt those remove most of the needs to hit those drives? Although, my take is that head wear is negligible (one small hit every so often), and spindle wear is normal (just runs 24/7, no hard starts/stops)
Also, I see that your pool is sending maybe 10x more requests for partials, comparing to those based on Chia code. So, maybe that reduced wear just addresses that part?
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The only thing that I could think of is that Flex farmer has better error handling, and is not hiding all kind of errors in debugging logs. I guess, any farmer that does that, would help both pools and farmers, as it looks like people are not realizing that their setups have issues (chiaās app is really good at hiding those, and Chia team in ignoring such reports).
I am a happy member of your pool, and I wish your famerās page would show in big red letters what are the errors encountered during the last 24 hours, and how to remedy those (not just in more verbose form of restating those problems) - maybe an error FAQ in the link.
One thing is making sure that farmer is healthy (what i have no doubt your is - I didnāt try it yet), and the second is to let users know that they have stuff to fix, eventually somehow forcing them to do that (even if only by a constant nagging).
Recently, one YouTuber has shown his farmer page for your pool, and my take is that even though he knows (much) more than an average farmer, he got about 20% bad partials without realizing that. He is doing those videos for several months as such potentially Flex member for that long, so unfortunately, by you not helping him, both Flex and members suffer, as those bad partials are hurting poolās winning chances.