Evaluating the decentralisation of filecoin

Web3 is progressively decentralising Internet services with the introduction of the blockchain, from social networks to online trading. Filecoin is a Web3 storage marketplace implemented on top of the Interplanetary File System that aims at decentralising storage by rewarding users who pledge storage to the system. Clients form deals with storage miners, who store deals on the Filecoin blockchain for transparency and auditability. Storage miners can also obtain extra rewards when they mine a block. In this paper, we show that although Filecoin aims at complete decentralisation, the rewarding system acts as the opposite. We download a dataset composed of 47.5M messages and expose that most of the blocks are created by the same storage miners, who are also the ones that pledge more storage. An analysis of their identity shows that they belong to cloud companies, that have a lot of extra storage resources. The effect observed is due to the fact that storage miners are able to commit all extra storage to the system, even when there are no deals in them. Additionally, this effect is further intensified by recent updates to Filecoin, which let storage miners update committed storage to deal-containing storage effortlessly.