When synchronising a new full node, the first step is to download all the available blocks, it's interesting to note that the node is not usable right away as it needs to pull from the network all the states the blockchain needs to be in the actual "state".
The question is, does all this new data take up space or it simply rewrites data in each block leaving the chain data size unchanged?
Thank you
The question is, does all this new data take up space or it simply rewrites data in each block leaving the chain data size unchanged?
There are two normal operating modes for Ethereum nodes: full node and archive node.
The full node automatically prunes the old state as you say. The full node is the default mode. The disk space requirements for the archive node are much higher, several terabytes.
Each account fits within 128 bytes, there are 160 million of accounts so the state takes up about 19 Gigs if we extract only the info that matters. However there are supporting data structures to hold this , like Patricia Merkle Trie and frozen chain data (blocks, transactions) which take up about 400 GB on disk as of 23 Jul 2021.
The data will keep growing with time, so if you want to "compress" it, re-download the chain periodically as it is the best way to compact it.
