LIZARDFS(7)

📦 version 3.12.0, in fedora 43

👑 LIZARDFS — the manual page, but make it a group chat 💖

okay bestie, sit down, hydrate, because we're talking about lizardfs — aka moosefs, aka mfs (yes she has three names, main character behavior fr fr). This is the LIZARDFS(7) page, so it's the vibe-lore version — the big picture, not the "how do I pass a flag" version. That one's elsewhere, iykyk.

🌈 NAME 🌈

lizardfs, moosefs, mfs — a networking, distributed, highly available file system. That's the whole vibe. Three names, one icon. 💅

✨ DESCRIPTION ✨

So LizardFS is a networking, highly available, distributed file system. She spreads data over several physical localisations (servers), and to you, the user, all of that shows up as one single resource. You don't see the chaos, you see the ~lewk~. 🦋

For standard file operations, LizardFS acts exactly like other Unix-alike file systems. No cap. She has:

  • a hierarchical structure (that's the directory tree, bestie 🌳)
  • she stores files' attributes — permissions, last access and modification times
  • and she can make special files: block and character devices, pipes and sockets 🎀
  • plus symbolic links — file names pointing to another files accessible locally, not necessarily on LizardFS
  • and hard links — different names of files which refer to the same data on LizardFS

Access to the file system can be limited based on IP address and/or password. Yes she gates herself, as she should. 🔐

💖 Distinctive features of LizardFS 💖

these are the personality traits, the things she brings to the table that other file systems simply do not:

  • higher reliability — data can be stored in several copies on separate computers 💀 (in a good way)
  • dynamically expanding disk space by attaching new computers/disks 🫶
  • possibility of storing deleted files for a defined period of time — the "trash bin" service, on a file system level 🌸
  • possibility of creating snapshot of a file — meaning a coherent copy of the whole file, even while the file is being written. THE WAY THAT WORKS?? iconic. ✨

🏗️ ARCHITECTURE 🏗️

A LizardFS installation consists of five types of machines. Five. Like a girl group. Let's meet them. 🎤

  • master metadata server (or ‘the master’) — a managing server. Single computer managing the whole filesystem, storing metadata for every file. That's information on size, attributes and file localisation(s), including all information about non-regular files, i.e. directories, sockets, pipes and devices. She knows everything. She's the main character. 👑
  • metadata server shadows (or ‘the shadow’) — almost identical to the master. There can be any number of those, they work as master metadata server backup, and they are ready for immediate deployment as new master in case of current master failure. Understudies who are genuinely ready to go on. respect. 🫡
  • data servers — any number of commodity servers storing files data and replicating it among themselves (if a certain file is supposed to exist in more than one copy). The whole squad holding hands. 🫶
  • metadata backup servers — any number of servers, all of which store metadata changelogs and periodically downloading base metadata file. And it's easy to run mfsmaster process on such machine when primary master stops working. Backup besties who can be promoted at any time. 💅
  • client computers referring to LizardFS stored files — any number of machines with a working mfsmount process. That process communicates with the managing server to receive and modify file information, and with chunkservers to exchange actual file data. That's you. Hi. 👋

Metadata is stored in memory of the managing server and simultaneously is being saved on disk — as a periodically updated binary file and immediately updated incremental logs. The main binary file as well as the logs are replicated to metaloggers (if present). ✨

File data is divided into fragments (chunks) of maximum size 64MB each, which are stored as files on selected disks on data servers (chunkservers). Each chunk is saved on different computers in a number of copies equal to a "goal" for the given file. So the goal is literally the goal. periodt. 🎯

🐛 REPORTING BUGS 🐛

Found a bug? Not me finding a bug 💀 — but if you do, report bugs to <contact@lizardfs.org>. She wants to know. She'll fix it. slay. 🫶

Copyright 2008-2009 Gemius SA, 2013-2015 Skytechnology sp. z o.o.

LizardFS is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 3.

LizardFS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. (Translation: she's free, she's generous, she is not legally promising you anything, bestie. 😭) See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with LizardFS. If not, see http://www.gnu.org/licenses/. 👑

👀 SEE ALSO 👀

the rest of the friend group, go say hi:

and that's the page, babes. This was the LizardFS(7) manual, dated 07/24/2025 — yes we're timestamped, we're documented, we're archived. go touch grass (or, y'know, mount a distributed file system). love u, bye 💖🦋✨

📦 where this page comes from