# Economics of BitTorrent communities

## Authors

- Ian A. Kash - iankash@microsoft.com
- John K. Lai - jklai@seas.harvard.edu
- Haoqi Zhang - hq@eecs.harvard.edu
- Aviv Zohar - avivz@microsoft.com

### DOI

- https://doi.org/10.1145/2187836.2187867

## Summary

The paper is a study of a BitTorrent community called DIME, where users share live concert recordings. The community has around 100K users and the study analyses data gathered over 6 months.

### Main ideas

 * The DIME system enforces a ratio of at least 0.25: 4 downloads for 1 upload
 * Many users have a ratio above 1 (which shows an altruistic behaviour)
 * New files are more attractive to users and have high demand at the beginning
 * Users with high bandwidth Internet connections take advantage of new files to take credits
 * Old files are no good to gain credit because they are not in high demand
 * There are periods where downloads are free
 * Users prefer to download old files during free periods

### Observations

 * The paper does not give any numbers about the amount of data available in total
 * The paper does not provide data about the file size distribution
 * Overall the paper provides interesting data about how sharing communities behave but no data about the decentralized storage itself.
 
### Other ideas

 * Some aspects of the demand for files with respect to their life could be applied to other decentralized storage systems