[bitcoin-dev] CORRECTIONS: A summary of block size hardfork proposals

jl2012 at xbt.hk jl2012 at xbt.hk
Fri Jul 31 03:10:34 UTC 2015

I am making some corrections to my previous summary

Currently, there are 4 block size BIP by Bitcoin developers:

BIP100 by Jeff:  
BIP101 by Gavin:  
BIP102 by Jeff: https://github.com/bitcoin/bips/pull/173/files
BIP??? by Pieter (called "BIP103" below):  

To facilitate further discussion, I'd like to summarize these  
proposals by a series of questions. Please correct me if I'm wrong.  
Something like sigop limit are less controversial and are not shown.

Should we use a miner voting mechanism to initiate the hardfork?
BIP100: Yes, support with 10800 out of last 12000 blocks (90%)
BIP101: Yes, support with 750 out of last 1000 blocks (75%)
BIP102: No
BIP103: No

When should we initiate the hardfork?
BIP100: 2016-01-11#
BIP101: 2 weeks after 75% miner support, but not before 2016-01-11
BIP102: 2015-11-11
BIP103: 2017-01-01

# The network does not actually fork until having 90% miner support

What should be the block size at initiation?
BIP100: 1MB
BIP101: 8MB*
BIP102: 2MB
BIP103: 1MB

* It depends on the exact time of initiation, e.g. 8MB if initiated on  
2016-01-11, 16MB if initiated on 2018-01-10.

Should we allow further increase / decrease?
BIP100: By miner voting, 0.5x - 2x every 12000 blocks (~3 months)
BIP101: Double every 2 years, with linear interpolations in between  
(41.4% p.a.)
BIP102: No
BIP103: +4.4% every 97 days (double every 4.3 years, or 17.7% p.a.)

The earliest date for a >=2MB block?
BIP100: 2016-04-03^
BIP101: 2016-01-11
BIP102: 2015-11-11
BIP103: 2020-12-27

^ Assuming 10 minutes blocks and votes cast before 2016-01-11 are not counted

What should be the final block size?
BIP100: 32MB is the max, but it is possible to reduce by miner voting
BIP101: 8192MB
BIP102: 2MB
BIP103: 2048MB

When should we have the final block size?
BIP100: Decided by miners
BIP101: 2036-01-06
BIP102: 2015-11-11
BIP103: 2063-07-09

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