[bitcoin-dev] Segwit2Mb - combined soft/hard fork - Request For Comments

Sergio Demian Lerner sergio.d.lerner at gmail.com
Thu Apr 6 20:42:19 UTC 2017

The 95% miner signaling is important to prevent two Bitcoin forks, such as
what happened with Ethereum HF and Ethereum Classic.

Bitcoin has a very slow difficulty re-targeting algorithm. A fork that has
just 95% miner support will initially (for 2016 blocks) be 5% slower (an
average block every 10 minutes and 30 seconds). The transaction capacity of
the new Bitcoin protocol is reduced only 5%.
However the chain with 5% if the hashing power not only has a 20x capacity
reduction, but confirms transactions in 20x more time. So the mempool will
grow 400 times. It must be noted that fees increased 10x from the moment
blocks were half full, to the moment blocks became saturated. I'm sure no
Bitcoin (pre-fork) user will be willing to pay 100x times the transaction
fees to use such a slow and insecure network.

So a 6-block confirmation will take 20 hours in the original chain and the
original chain will be in this almost useless slow state for an average of
2016 blocks, or 280 days.
If the original blockchain hard-forks to re-adjust the difficulty, then it
will just represent an alt-coin having 5% of Bitcoin community, and it
can't affect Bitcoin (the segwit2mb fork).

On Mon, Apr 3, 2017 at 11:40 AM, Btc Drak <btcdrak at gmail.com> wrote:

> On Fri, Mar 31, 2017 at 10:09 PM, Sergio Demian Lerner via bitcoin-dev <
> bitcoin-dev at lists.linuxfoundation.org> wrote:
>> The hard-fork is conditional to 95% of the hashing power has approved the
>> segwit2mb soft-fork and the segwit soft-fork has been activated (which
>> should occur 2016 blocks after its lock-in time)
> Miners signalling they have upgraded by flipping a bit in the nVersion
> field has little relevance in a hard fork. If 100% of the hash power
> indicates they are running this proposal, but the nodes don't upgrade, what
> will happen?
> For the record, I actually talk a lot about hard forks with various
> developers and am very interested in the research that Johnson in
> particular is pioneering. However, I have failed to understand your point
> about 95% miner signalling in relation to a hard fork, so I am eagerly
> awaiting your explanation.
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