Sia maintains 50 contracts with hosts at all times, and uses 30 of them for each file segment that gets uploaded. We use state channels, so we can use the same

Sia maintains 50 contracts with hosts at all times, and uses 30 of them for each file segment that gets uploaded. We use state channels, so we can use the same contracts each time you upload a new file, minimizing the total amount of on-chain activity.