a) Massive data volumes (~100 Gb - 1 Pb/project)
ai) This means that data is typically stored on limited access machines like HPC clusters
bi) This also means that shipping this data around is financially expensive, and cannot be supported purely by small client machines
b) A low number of seeders; scientific data is not exactly popular, and there may be network restrictions on uploads through the typically used networks;c) The requirement for a data legacy; torrents are fantastic for ephemeral data (e.g. operating system builds), but are terrible for data that must be archived and kept for potentially decades to centuries.