This is great Pieter. I was able to sync the entire blockchain from scratch in a little over 4 hours on a laptop over cable modem. :) No issues to report. Even my family photos are intact! This makes it practical to run a full node, part time on a laptop again.
Aaron Voisine breadwallet.com On Sat, Oct 11, 2014 at 4:34 PM, Pieter Wuille <pieter.wui...@gmail.com> wrote: > Hi all, > > I believe that a large change that I've been working on for Bitcoin > Core is ready for review and testing: headers-first synchronization. > In short, it changes the way the best chain is discovered, downloaded > and verified, with several advantages: > * Parallel block downloading (much faster sync on typical network > connections). > * No more stalled downloads. > * Much more robust against unresponsive or slow peers. > * Removes a class of DoS attacks related to peers feeding you > low-difficulty valid large blocks on a side branch. > * Reduces the need for checkpoints in the code. > * No orphan blocks stored in memory anymore (reducing memory usage during > sync). > * A major step step towards an SPV mode using the reference codebase. > > Historically, this mode of operation has been known for years (Greg > Maxwell wrote up a description of a very similar method in > https://en.bitcoin.it/wiki/User:Gmaxwell/Reverse_header-fetching_sync > in early 2012, but it was known before that), but it took a long time > to refactor these code enough to support it. > > Technically, it works by replacing the single-peer blocks download by > a single-peer headers download (which typically takes seconds/minutes) > and verification, and simultaneously fetching blocks along the best > known headers chain from all peers that are known to have the relevant > blocks. Downloading is constrained to a moving window to avoid > unbounded unordering of blocks on disk (which would interfere with > pruning later). > > At the protocol level, it increases the minimally supported version > for peers to 31800 (corresponding to bitcoin v3.18, released in > december 2010), as earlier versions did not support the getheaders P2P > message. > > So, the code is available as a github pull request > (https://github.com/bitcoin/bitcoin/pull/4468), or packaged on > http://bitcoin.sipa.be/builds/headersfirst, where you can also find > binaries to test with. > > Known issues: > * At the very start of the sync, especially before all headers are > processed, downloading is very slow due to a limited number of blocks > that are requested per peer simultaneously. The policies around this > will need some experimentation can certainly be improved. > * Blocks will be stored on disk out of order (in the order they are > received, really), which makes it incompatible with some tools or > other programs. Reindexing using earlier versions will also not work > anymore as a result of this. > * The block index database will now hold headers for which no block is > stored on disk, which earlier versions won't support. If you are fully > synced, it may still be possible to go back to an earlier version. > > Unknown issues: > * Who knows, maybe it will replace your familiy pictures with Nyan > Cat? Use at your own risk. > > TL;DR: Review/test https://github.com/bitcoin/bitcoin/pull/4468 or > http://bitcoin.sipa.be/builds/headersfirst. > > -- > Pieter > > ------------------------------------------------------------------------------ > Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer > Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports > Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper > Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer > http://p.sf.net/sfu/Zoho > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development ------------------------------------------------------------------------------ Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho _______________________________________________ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
