5.1 Overview

Data availability is also the key component of NERO, which is quite critical for rollups. In NERO, we designed a new type of chain and transaction, especially for data availability as an independent layer, known as the data availability (DA) layer. The DA layer is also under the management of the settlement layer and maintained by a group of nodes (DA nodes) that have staked tokens in the settlement layer. Validators in the settlement layer can check the availability of DA blocks through random sampling and fraud proof, thus confirming the DA chain. In addition, we can broaden the scope of DA nodes to encompass multiple groups, with each group maintaining a distinct DA chain. This approach enables us to establish a sharding system, thereby catering to diverse storage demands. The overall system architecture is illustrated below.