MCDrive is a virtual storage device for Linux. It stores bytes as blocks in a Minecraft server.

"Why do not you use NBT?", "Why not use blockstates?", etc...? One of my personal goals was to make stored data visually interesting in-game.

• WHY
• HOW
• RUN

MCDrive was written as a joke in two short evenings. The code is terrible and the architecture can be improved.

I saw this video on YouTube about a Minecraft plugin, that runs an HTTP server, which uses the in-game world itself as BLOB storage.

That implementation included a custom file system, which was far from perfect. I thought "I could do you one better" and went one layer lower in the abstraction, allowing any file system.

My task became very simple - mapping 3D world of Minecraft into a 1D array of bytes, and letting existing file systems handle the rest ✨. With 1382400000000000000 blocks in the overworld, and 1 byte per 1 block, the available storage space is ~1257285 TebiBytes. This size has shown me just how buggy various partition managers can be :P

Image generated by the amazing Excalidraw.

1. Linux has support for Network Block Devices. By loading the NBD module, we create block devices called nbdXXX at /dev/. These can be used as drives, in fact, your physical drives are sitting in that folder too.
2. A C program, ran as super-user, translates /dev/nbd0 APIs into another intermediary FIFO-based protocol. Those FIFOs are created in userspace.
3. Because FIFOs are accessible by a regular user, we can safely run a Minecraft server as that user. A PaperMC plugin polls FIFOs and performs according changes in the Minecraft world, and the server itself provides real-time world updates to the clients.

Performs changes in the world? And HOW is that?

I decided to go with a "1 byte = 1 block" approach. This meant generating an alphabet of 256 blocks, which is pretty easy. 0 has been hardcoded to "air", and the rest of the alphabet are full blocks with no gravity.

Drives must be 1-dimensional, but a Minecraft world is 3-dimensional. I decided to unwrap blocks in a chunk from bottom to top, and chunks in a world - in a spiral around the origin. This made stored information easy to observe in-game, because it does not shoot off into the distance; it prioritizes staying close to the origin. (In addition, less regions are created this way.)

Note that the plugin is licensed under GNU GPL 3, and the NBD bridge is licensed under GNU GPL 2.

Prerequisites

• gcc v14.
• sudo.
• A clone of this repository.
• Latest PaperMC for 1.21.7 in Server/server.jar.

Running

1. Open a terminal, change CWD into NBD-FIFO/, and execute ./run.sh. This does require super-user, but it must be ran as a regular user (to create FIFOs as).
2. Open a terminal, change CWD into Server/, and execute ./run.sh.
3. [ONCE] Apply /gamerule randomTickSpeed 0 to prevent data corruption.

Now you can use /dev/nbd0 as a drive. Write to it raw, or partition it with a file system - anything your heart desires!