<div dir="ltr"><div><div>In terms of miners, a strong supermajority is arguably sufficient, even 75% would be enough.<br><br></div>The near total consensus required is merchants and users. If (almost) all merchants and users updated and only 75% of the miners updated, then that would give a successful hard-fork.<br><br></div><div>On the other hand, if 99.99% of the miners updated and only 75% of merchants and 75% of users updated, then that would be a serioud split of the network.<br><br></div><div>The advantage of strong miner support is that it effectively kills the fork that follows the old rules. The 25% of merchants and users sees a blockchain stall.<br><br></div><div>Miners are likely to switch to the fork that is worth the most. A mining pool could even give 2 different sub-domains. A hasher can pick which rule-set to follow. Most likely, they would converge on the fork which paid the most, but the old ruleset would likely still have some hashing power and would eventually re-target.<br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, May 7, 2015 at 9:00 PM, Roy Badami <span dir="ltr"><<a href="mailto:roy@gnomon.org.uk" target="_blank">roy@gnomon.org.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I'd love to have more discussion of exactly how a hard fork should be<br>
implemented. I think it might actually be of some value to have rough<br>
consensus on that before we get too bogged down with exactly what the<br>
proposed hard fork should do. After all, how can we debate whether a<br>
particular hard fork proposal has consensus if we haven't even decided<br>
what level of supermajority is needed to establish consensus?<br>
<br>
For instance, back in 2012 Gavin was proposing, effectively, that a<br>
hard fork should require a supermajority of 99% of miners in order to<br>
succeed:<br>
<br>
<a href="https://gist.github.com/gavinandresen/2355445" target="_blank">https://gist.github.com/gavinandresen/2355445</a><br>
<br>
More recently, Gavin has proposed that a supermoajority of only 80% of<br>
miners should be needed in order to trigger the hard fork.<br>
<br>
<a href="http://www.gavintech.blogspot.co.uk/2015/01/twenty-megabytes-testing-results.html" target="_blank">http://www.gavintech.blogspot.co.uk/2015/01/twenty-megabytes-testing-results.html</a><br>
<br>
Just now, on this list (see attached message) Gavin seems to be<br>
aluding to some mechanism for a hard fork which involves consensus of<br>
full nodes, and then a soft fork preceeding the hard fork, which I'd<br>
love to see a full explanation of.<br>
<br>
FWIW, I think 80% is far too low to establish consensus for a hard<br>
fork. I think the supermajority of miners should be sufficiently<br>
large that the rump doesn't constitute a viable coin. If you don't<br>
have that very strong level of consensus then you risk forking Bitcoin<br>
into two competing coins (and I believe we already have one exchange<br>
promissing to trade both forks as long as the blockchains are alive).<br>
<br>
As a starting point, I think 35/36th of miners (approximately 97.2%)<br>
is the minimum I would be comfortable with. It means that the rump<br>
coin will initially have an average confirmation time of 6 hours<br>
(until difficulty, very slowly, adjusts) which is probably far enough<br>
from viable that the majority of holdouts will quickly desert it too.<br>
<br>
Thoughs?<br>
<span class="HOEnZb"><font color="#888888"><br>
roy</font></span><br>------------------------------------------------------------------------------<br>
One dashboard for servers and applications across Physical-Virtual-Cloud<br>
Widest out-of-the-box monitoring support with 50+ applications<br>
Performance metrics, stats and reports that give you Actionable Insights<br>
Deep dive visibility with transaction tracing using APM Insight.<br>
<a href="http://ad.doubleclick.net/ddm/clk/290420510;117567292;y" target="_blank">http://ad.doubleclick.net/ddm/clk/290420510;117567292;y</a><br>_______________________________________________<br>
Bitcoin-development mailing list<br>
<a href="mailto:Bitcoin-development@lists.sourceforge.net">Bitcoin-development@lists.sourceforge.net</a><br>
<a href="https://lists.sourceforge.net/lists/listinfo/bitcoin-development" target="_blank">https://lists.sourceforge.net/lists/listinfo/bitcoin-development</a><br>
<br></blockquote></div><br></div>