---
title: "Alex"
summary: "Minecraft server wrapper that automates world backups"
type: "project"
params:
    links:
        - name: Source
          url: 'https://git.rustybever.be/Chewing_Bever/alex'
---

Alex was created to solve an issue I'd been having: inconcistent Minecraft
server backups.

My original backup system involved compressing the server world and config
directories in a tarball. While this usually worked, the command regularly
failed due to conflicts while reading a file the server was writing to. Because
the Minecraft server is unaware of the fact it's being backed up, it
continuously writes data to disk, preventing the tar command from doing its
job.

My solution for this consisted of designing a process that wraps the Minecraft
server process and interacts with its standard input. The Minecraft server
accepts certain commands (`save-all` and `save-on`/`save-off`) that allow an
admin to control when and if the server writes data to disk. Using this, the
wrapper process tells the server to flush all data, stop writing to disk, and
only resume writing after a successful backup has been created.

This idea was then expanded to implement incremental backups, which greatly
reduced the time and disk size needed for the backups. For reference, our
~2.5GB world folder can be backed up incrementally in less than 5 seconds, with
backups running every thirty minutes, without ever turning off the server.
