Decentralized Storage in Blockchain: How Blockchains are Stored and Maintained

Introduction: Blockchain technology has revolutionized the way data is stored and shared. One of the key features of decentralized blockchains is the distribution of data across a network of nodes.

• A blockchain is stored in a decentralized network of nodes.
• Each node maintains a complete copy of the blockchain.
• The blockchain is stored as linked blocks of transactions through cryptography.

• Blockchain nodes can be maintained by individual participants, companies, or even specialized organizations.
• Nodes can run on personal computers or dedicated servers.
• The geographical location of nodes can be diverse, contributing to network decentralization.

• Anyone can set up and maintain a blockchain node.
• Participants can join mining pools to combine resources and maintain nodes collectively.
• Companies and specialized organizations can offer node services as part of their business model.

• If a participant stops maintaining a node, their copy of the blockchain becomes outdated.
• However, the network of nodes continues to function and validate transactions.
• Other nodes will maintain the integrity of the blockchain, and the participant can rejoin at any time to synchronize their node.

• The number of nodes required to validate a blockchain varies based on the design and consensus rules of each blockchain.
• Some blockchains require a minimum number of nodes to achieve consensus and validate transactions.
• Decentralization is strengthened when there is a wide geographical distribution of nodes.

• If there are two blockchains on different nodes and one of them has not been updated, a fork occurs in the blockchain.
• The fork can happen due to differences in the implementation of updates or consensus rules among the nodes.
• Nodes that have not been updated will continue to operate with the previous version of the blockchain, while the updated nodes will work with the new version.
• This creates two independent and divergent blockchains, each with its own transaction history.
• The fork can be resolved through a process known as “consensus,” in which nodes in the network choose a main chain based on predefined rules.
• Generally, the longest and most validated chain is considered the main chain, and nodes on the non-updated fork will eventually abandon it and synchronize with the main chain.

• Updates and improvements in a decentralized blockchain may require changes to the software or consensus rules.
• When an update is released, nodes must follow the new protocol to stay on the same updated blockchain.
• If a node hasn’t been updated, it will continue to operate on the previous version of the blockchain.
  This can result in a fork in the chain, where there are two independent chains with different transaction histories.
• To resolve the fork, a consensus process takes place, in which nodes choose a main chain based on predefined rules.
• The main chain is generally the longest and validated by the majority of nodes, and nodes on the non-updated fork will eventually abandon it and synchronize with the main chain.

• Full nodes are responsible for maintaining a complete copy of the blockchain.
  These nodes verify and validate all transactions and blocks in the network.
• Full nodes store a significant amount of data, requiring more storage space and computational resources.
• On the other hand, lightweight nodes are nodes that do not store a complete copy of the blockchain.
  These nodes rely on full nodes to retrieve blockchain information when needed.
• Lightweight nodes require fewer resources and are more suitable for devices with limited capabilities, such as mobile phones.