Quote from: Syke on March 18, 2016, 11:57:23 PM

Quote from: jl777 on March 18, 2016, 09:54:43 PM

It seems 10 blocks at current hashrate would be very rare

Extremely! This is closely related to the odds of pulling off a double-spend 10 blocks deep. D&T explained nicedly at https://bitcoin.stackexchange.com/questions/1170/why-is-6-the-number-of-confirms-that-is-considered-secure.

The worst was the overflow bug. That would have been around 53. https://en.bitcoin.it/wiki/Value_overflow_incident

My node only goes back to 2012, so I missed out on the overflow fork. But I have the next big one. My node saw the .7/.8 fork at a reorg of 30:

Code:

{
"height": 225459,
"hash": "000000000000036e459f26b1dc02683c9beeb061eedf18689995143354467245",
"branchlen": 30,
"status": "valid-headers"
},

Feel free to analyze my data at http://pastebin.com/LZxst5vD.

Fantastic!! thanks for this invaluable history, 2012 is quite a ways back. Also reorgs from bugs/new versions are different from "normal" reorgs caused by propagation

and the hashrate was a small fraction back around block 225K. Not sure, but I think it is harder to reorg now vs then? If only since we now have ASIC so the tech leaps in hashrate from CPU to GPU to FPGA to ASIC is already done.

It seems vast majority are just 1 deep.
around 10 2 deep
just a few 3 deep

the 6 block reorg seems to be an outlier along with the 30. All the talk about eventual consensus, but with bitcoin it looks like 99.999% of the time, within 3 blocks it is in consensus

unless your node is special.

with propagation of around 15 seconds though, it seems other than at the edge of one block, it would take three fast blocks to require a 3 block reorg. Maybe that 6 block reorg was an actual attack? it seems way out of bounds and both your node and 2112's has it so it is unlikely that is it some local connectivity issue

since nowadays the miners are all probably doing their best to push the new blocks as fast as possible, that combined with the nextgen ASIC probably not going to be much more than 2x increase, maybe as little as 5 blocks would be enough, but there isnt much difference between 5 and 10, so probably best to setback 10 blocks