BitTorrent and Archives

2025-08-05

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I first discovered BitTorrent back in 2006, and I still use it today for downloading Linux distros and other large amounts of static data. Over the last two decades, I've become familiar with both the technical workings of BitTorrent and the culture surrounding it use, though I wouldn't consider myself an expert on it.

Of course, BitTorrent isn't the only method people use to send data to each other. When one wants to send a collection of files to someone else, a common choice is to pack all the files to some kind of archive, such as WinRAR or a tarball, and send the archive using a service like Dropbox.

A pet peeve of mine is when people combine these tools: rolling a large number of files into an archive, then creating a torrent out of that single archive.

One reason to use archives is that most archive formats contain rudimentary forms of error checking: if the archive data is valid, all the files inside will still be valid. That isn't necessary with BitTorrent. The torrent file contains a list of hashes of each chunk of the data, ensuring file integrity as clients download chunks and verify their SHA1 sums. Using the extra check of an archive file is redundant.

More annoyingly, sharing an archive via BitTorrent renders useless a particularly nice function. Modern clients can select which files in a torrent to download, allowing to user to get only certain subsets of data and avoid downloading the entire set. If all the data in the torrent is stored into a single archive, the user now must download the entire archive, even if he wants only a few files inside.

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[Last updated: 2025-08-05]