Where actual blockchain state data stored in memory in file or in database

Question

Where blockchain data is saved in every node? After a long search in google, StackOverflow, and some blogs, like got many answers: like it is saved in a database like level-DB or rocks-DB, some said it saves in memory in a variable, some said it saved in a file (from hyperledger-fabric).

I want to know, is there a particular method of storing blocks that are followed by most blockchain frameworks?

Or all those frameworks choose different methods (like file, memory, or DB).

I know there is a current state/world state of blockchain which is saved in a database. This current state/world state is totally different from the actual blockchain. In the current state or world state, the data can be modified, but in actual blockchain block/data is immutable.

My question is:

How is the data (immutable blocks) stored on the ledger of every full node in a Blockchain ? is it in Memory, in a file (like JSON, CSV file ), or in DB

Answer 1

Bitcoin nodes keep the raw block data on disk in files .bitcoin/blocks/blk*.dat. The size of each blknnnnnn.dat is 128MB, with the total size of data as of today being 300GB. Metadata about all known blocks is kept in Level DB files in .bitcoin/blocks/index/nnnnnn.ldb files.