There are three parties involved in the Filecoin system: clients, storage miners, and retrieval miners. These groups of users interact closely with each other, concluding transactions, exchanging information, and making micropayments in $FIL.
Clients pay for storing or retrieving data. They place an order on the online storage market, where a deal is subsequently concluded with storage miners. Storage miners, in turn, store client’s data and receive rewards. This group of users places files in free sectors of a hard drive, all actions are recorded in the blockchain, and clients receive private keys.
Retrieval miners extract data at a request of a client. Clients place a trade on the off-chain Retrieval Market. Retrieval miners can also act as storage miners.
Filecoin is based on IPFS where all data is stored on a peer-to-peer blockchain. To start the process, users choose miners to store personal data and pay for placement in FIL tokens. Thereby, miners execute trades, and receive participation fees and FIL rewards. The more storage miners offer, the higher the chances of getting rewarded. At any time, clients can check how their data is stored during a transaction, as proofs are fixed in the blockchain. The Filecoin network uses the Proof-of-Replication (PoRep), while the miners use the Proof-of-Spacetime (PoSt).
Therefore, if a client wants to hopefully keep their data safe on the Filecoin network, then they must pay the miner. The cost is set by the open market, and the price is made up of several factors. In the open market, there is hyper competition among miners, where everyone puts forward their own minimum price for storage.