I am running Linux with a harddisk. Currently the blockchain is on an NTFS partition, which probably isn't the fastest. Which filesystem should I choose? As I understand it, a Bitcoin node will only ever append to the blockchain, which means I should not choose a filesystem that is optimized for e.g. fast deletion.
Bitcoin-Core does serval read and write operations. Blocks can also get deleted in case you have enabled
-prune. There are many read operations because your node will very likely serve/relay blocks to other nodes.
The performance of bitcoin-core is more likely constraint by your CPU because of heavy EC verify operations.