Distributed Storage Systems

One of the fundamental open challenges for Web 3.0 is effective data storage. The socio- economic value and scale of information increases day by day, and Web 3.0 developers have been working to identify ways to ensure not only that digitally stored data endures but also that it is readily available, reliable, secure, and consistent. In recent years, the massive generation of data coupled with frequent storage failures has increased the popularity of distributed storage
systems, which allow data to be replicated in different, geographically dispersed, storage devices. Due to the dissemination of data in multiple hosts, one of the major problems that distributed storage systems face is maintaining the consistency of data when they are accessed concurrently by multiple operations.

Interplanetary File system
The IPFS is a distributed file system that resutlted from the evolution or prior peer to peer sytems, incluyding DHTs, BitTorrent, Git and SFS. The contribution of IPFS is simplifying, evolving, nad connecting proven techniques into a single cohesive system, greater than the sum of its parts. IPFS could even evolve the web itself. IPFS is peer to peer; no nodes are privileged. IPFS nodes store IPFS objects in local storage. Described by Viktor Tron as the leg kit for the third web, IPFS is a new system for storing data on a large number of computers. It is transport layer agnostic, meanign that it can communicate through tCP, uTP, UDT, QUIC, TOR, and even bluetooth. Instead of a centrla server, a peer to peer network is used to establish connections IPFS implements a distributed hash table DHT that provides a lookup service similar to a hash table: (key, value) pairs are stored in a DHT, and any participating node can efficiently retrieve the value associated with a given key. Responsibility for maintaining the mapping form keys to values is distributed among the nodes in such a wya that a change in the set of participiants uses a minimal amount of disruption. This allows a DHT to scale to extremely large numbers of nodes and to handle continual node arrivals, departures and failures.

The size field is mainly used for optimizing the P2P networking, and we're going to mostly ignore it here, since conceptually it's not needed for the logical structure.
IPFS obejcts are normally referred to by their Base58 encoded hash. All hashed begin with "QM". this is because the hash is a multihash, meaning that the hash itself specifies the hash function and length of the hash in the first two bytes of the multihash. The data and named links give hte collection of IPFS objects the structure of a Merkle directed acyclic grpah DAG to signify that this is a cryptograhically authenticated data structure that, as we noted above, usess cryptographic hashes to address content. Visualize IPFS object by a graph with data in the node and the links being directed graph edges to other IPFS objects, wher ethe name of the link is a label on the graph edge. Various data structures can be represented by IPFS objects, for example a file system. IPFS can easily represent a file system consisting of files and directory