Quote from: jgarzik on May 28, 2013, 08:51:17 PM

Quote from: plonk420 on May 28, 2013, 11:23:34 AM

it's a pity the torrent isn't 7zipped...

could the next iteration of it be compressed?

Feedback on this is welcomed. Generally, not all platforms have an easy time getting up and running with 7zip. Users in the past requested something directly usable with bitcoind.

Opinions differ, and maybe if it saves a gigabyte or two, it would be worth it.

Some users also complain about the doubling of disk space required -- for both compressed and uncompressed copies.

It saves more than 3GB currently; 7zip at optimum settings reduces blockchain data to about 57% of the original size.

It would reduce the amount of disk space required; the decompressed copy doesn't need to be kept after an import. The compressed file is seeded from the user's torrent directory, and makes for a good checksummed archive of the blockchain for a user to have as a backup too.

I wrote unzip/install scripts that can be included with the torrent for one-click extraction

http://(deleted)...

Quote from: deepceleron on February 11, 2013, 09:02:29 AM

....
I am slowly convincing myself even more that a compressed torrent is preferable. Without compression you are downloading the same amount of data as normal p2p. The compressed binary would only be repeatable on the exact xz/lzma/7zip build version and settings, but I think there are probably four people total that have run mkbootstrap anyway, so this is not important. It takes about an hour to smash the blockchain down to 60% the size at the extreme settings I've used over many trials to optimize settings.

Compressed-Pros:
-~~2000+~~ 3000+ MB of uploading and downloading saved for every user,
-2000+ MB less storage used when seeding,
-won't cause problems if torrent HDD is FAT32
(another: small split files easier to host/share/download from multiple sources than a single 8GB file)

Compressed-Cons:
-Not as simple to use, end-user must decompress with third-party utility (although 7-zip is common),
-More work creating torrent (doesn't matter to end-users),
-Cannot "update" torrent by simply replacing data file with newer version with additional blocks (likely to be a rare practice anyway, I am the only one seeding the old torrent right now).

Here is example compression, both require about an hour (but decompress in minutes):

xz utils 5.0.4/Win64, 3GB+ RAM required to compress (2,780,285,148 bytes)
xz --compress --keep --format=xz --check=sha256 --verbose --lzma2=dict=256MiB,nice=273,mf=bt4 bootstrap.dat

7-zip GUI win64 - 6GB+ RAM required to compress (2,769,830,975 bytes)
Format: 7z, Compression Level: Ultra, Compression method: LZMA, Dictionary size: 384MB, Word Size 273

A checkpoint of 225430 was added two months ago at the fork. I would guess that this will either be updated to a newer block or another will be added to before 0.8.2.
https://github.com/bitcoin/bitcoin/blob/master/src/checkpoints.cpp