Using mining pools, how do miners switch what coin to mine so quickly? Using mining pools, how do miners switch what coin to mine so quickly? Can someone explain?

Also do miners store a copy of the blockchain locally?
how do miners switch what coin to mine so quickly


This is called profit switching, and is usually implemented by the pool software. For example, NOMP explains this feature:


  Coin-switching ports using coin-networks and crypto-exchange APIs to
  detect profitability. Miner's connect to these ports with their public
  key which NOMP uses to derive an address for any coin needed to be
  paid out.


See https://github.com/zone117x/node-open-mining-portal


  Also do miners store a copy of the blockchain locally?


Typically, no. Miners focus their resources on the hashing algorithm and implement minimum necessary data transfer. Nodes store and validate the data and the miners will just get the latest block template from the node to mine, and then send solutions back.