What are the consensus mechanisms of blockchain? What are their relations with mining?

As we all know, Ethereum is undergoing critical changes and is about to be upgraded to Ethereum 2.0. The biggest difference between Ethereum 2.0 and Ethereum 1.0 is that it will replace the current "PoW" consensus mechanism with "PoS" consensus mechanism, which has caused opposition from a lot of miners.

Why do miners oppose Ethereum upgrades? This involves the role of consensus mechanisms, which is closely related to miners' earnings. Then how do consensus mechanisms determine miners' earnings? What are the main consensus mechanisms currently available?

·PoW, Proof of Work

PoW, famous for Bitcoin, requires users to perform some complex operations that take appropriate time, and the answers can be quickly validated by the service provider. The time, devices and energy are consumed as the cost of guarantee to ensure that the service and resources are used for real needs.

The rewards for mining depend on the effective work of the mining contribution. That is, the better the performance of the mining machine and the longer the mining time, the more rewards will be obtained.

·PoS, Proof of Stake

The concept of PoS was first introduced as Peercoin (PPC) in 2012. PoS is an upgraded consensus mechanism for PoW. Instead of requiring miners to perform a certain amount of computing work, PoS requires miners to provide their ownership of cryptocurrency in a certain amount.

According to PoS mechanism, the miner needs to create a "coin right" transaction when a new block is created, and the transaction will send some coins to the miners themselves in a predetermined proportion. Based on the proportion and time of each node owning tokens, the PoS mechanism reduces the mining difficulty of nodes in equal proportion according to the algorithm, thus speeding up the searching of random numbers.

In PoS mode, mining revenue is directly proportional to the coin age, and has nothing to do with the computing performance of computers.

·DPoS, Delegated Proof-of-Stake

DPoS was introduced in April 2014 by Dan Larimer, lead developer of Bitshares. DPoS is similar to board voting, in that the coin holders vote for a certain number of nodes for validation and bookkeeping on their behalf. To encourage more people to participate in the voting, the system will produce a small amount of tokens as rewards.

·PoST, Proof of Space Time

PoST is a concept introduced into blockchain by Filecoin. "Space-time" is defined as measuring and computing the time and space of data stored in a network.

In Filecoin network, PoST adopts WindowPoST auditing mechanism. Miners must submit PoST once for each sector within 24 hours, and post the composed Zero Knowledge Proof (ZKP) on the blockchain in the form of a message to make the users who store the data believe that the data has always been stored in the network. Therefore, sectors committed to capacity by miners are checked at least once every 24 hours in the Filecoin network, and a permanent and verifiable record is kept on the chain.