mfsmetadump(8)

📦
version 4.59.2 · 6 versions
, in arch rolling, nixos 26.05, nixpkgs unstable, ubuntu stonking

🌸 NAME 🌸

mfsmetadump — dump MooseFS metadata info in human readable format 💖 (yes bestie, the manual page name is literally also mfsmetadump, we're doing the (8) system-manager situation, slay)

🦋 SYNOPSIS 🦋

mfsmetadump [-d] [-s section_name] metadata_file

✨ DESCRIPTION ✨

mfsmetadump dumps MooseFS metadata info in human readable format. The output is broken up into several sections, each one carrying a different kind of information. Every section is made of two things: the header data — those rows that start with a hash (#) sign — and the content data, which, fair warning, may be totally empty. Ngl sometimes a section just shows up with vibes and no content 🙈.

💅 OPTIONS 💅

  • -d — replace all non-printable characters (codes < 32 and > 126) with '.'. It was the default behaviour in version < 3.0.110, so if you're on something ancient this is just... already happening, bestie.
  • -s — dump only the specified section of the file. Possible sections are:
    • HEAD — header info
    • SESS — client sessions
    • LABS — labels (not used)
    • SCLA — storage classes
    • PATT — pattern overrides
    • NODE — tree nodes (i-nodes)
    • EDGE — tree edges (file names)
    • FREE — free nodes (deleted i-nodes)
    • QUOT — quota definitions
    • XATR — xattr data
    • PACL — posix acl data
    • OPEN — open files
    • FLCK — flock data
    • PLCK — posix locks (lockf,ioctl) data
    • CSDB — active chunkservers
    • CHNK — chunks
  • metadata_file — path to metadata.mfs file 🫶

🎀 NOTES 🎀

Okay so here's the tea, bestie: every metadata section — with the exception of the HEAD section — consists of a constant set of HEADER fields plus a variable set of section-specific fields. The HEAD section is the iconoclast of the family: it contains only section-specific fields. The HEADER fields and all the section fields are listed below 👇

📋 SECTION HEADER

  • section header — section header (section type + version)
  • length — length of section
  • section type — name of section
  • version — hexadecimal representation of section version

📂 FILE HEADER SECTION (HEAD)

  • header — MooseFS version
  • version — metadata file version
  • fileid — metadata file id

👯 SESSIONS SECTION (SESS)

  • nextsessionid — first free session id
  • statscount — number of stats remembered in each session
  • SESSION — line describing a single session
    • s — session id
    • e — exports checksum
    • p — IP address
    • r — root inode number
    • f — session flags
    • u — umask
    • g — min and max goal (redundancy level)
    • t — min and max trash retention
    • m — maproot uid,gid and mapall uid,gid
    • x — disabled operations
    • d — disconnection time (optional)
    • c — current hour stats data
    • l — last hour stats data
    • i — session name (usually local mount point)

🏷️ STORAGE CLASS SECTION (SCLA), formerly LABELS SECTION (LABS)

  • LABELDESC — line with label description (existed only in LABS)
    • l — label letter
    • n — label description
  • SCLASS (formerly LABELSET) — line with storage class used in system
    • # — storage class id
    • x — admin only
    • m — mode
    • d — arch delay
    • c — create labels
    • k — keep labels
    • a — archive labels
    • n — name
  • SCLASSMAIN (used in version 4.0+ instead of SCLASS) — line with common parameters of storage class
    • # — storage class id
    • x — admin only
    • m — create mode
    • a — arch mode
    • d — arch delay
    • t — min trash retention
    • n — name
  • SCLASSEXPR (used in version 4.0+ instead of SCLASS) — line with label expression
    • # — storage class id
    • t — type ([C]reate,[K]eep,[A]rchive or [T]rash)
    • e — expression

🧵 PATTERNS SECTION (PATT)

  • PATTERN — line with pattern definition
    • v — priority
    • # — storage class id
    • t — trash retention
    • e — flags (extra mfs attributes)
    • u — uid
    • g — gid
    • p — pattern

🌳 NODES SECTION (NODE)

  • maxinode — maximum inode number used by system
  • hashelements — number of inodes in hash tabble
  • NODE — line with node (inode) description
    • k — node type (-,D,S,F,B,C,L,T,R)
      • - — file
      • D — directory
      • S — socket
      • F — fifo
      • B — block device
      • C — character device
      • L — symbolic link
      • T — trash file
      • R — sustained file (removed open file)
    • i — inode number
    • # — storage class id
    • e — flags (extra mfs attributes)
    • w — windows attributes
    • m — mode
    • u — uid
    • g — gid
    • a,m,c — atime, mtime, ctime
    • t — trash retention
    • d — rdevhi,rdevlo (only block and character devices)
    • p — path (only symbolic links)
    • l — file length (only files)
    • c — chunk list (only files)
    • r — sessions that have this file open (only files)

🪢 EDGES SECTION (EDGE)

  • nextedgeid — next available edge id (descending)
  • EDGE — line with edge description
    • p — parent inode number
    • c — child inode number
    • i — edge id
    • n — edge name

🕊️ FREE NODES SECTION (FREE)

  • free nodes — number of free (reusable) nodes
  • FREEID — line with free inode description
    • i — inode number
    • f — deletion timestamp

💰 QUOTA SECTION (QUOT)

  • quota nodes — number of nodes with quota
  • QUOTA — line with quota description
    • i — inode number
    • g — grace period
    • e — exceeded
    • f — flags
    • s — soft quota exceeded timestamp
    • si — soft inode quota
    • hi — hard inode quota
    • sl — soft length quota
    • hl — hard length quota
    • ss — soft size quota
    • hs — hard size quota
    • sr — soft real size quota
    • hr — hard real size quota

🗂️ XATTR SECTION (XATR)

  • XATTR — line with xattr description
    • i — inode number
    • n — xattr name
    • v — xattr value

🔐 POSIX ACL SECTION (PACL)

  • POSIXACL — line with acl description
    • i — inode number
    • t — acl type
    • u — user (file owner) permissions
    • g — group permissions
    • o — other permissions
    • m — permission mask
    • n — named permissions - list of objects:
    • u(U):P — permissions P for user with uid U
    • g(G):P — permissions P for group with gid G

🔓 OPEN FILES SECTION (OPEN)

  • OPENFILE — line with open file description
    • s — session id
    • i — inode number

🐑 FLOCK LOCK SECTION (FLCK)

  • FLOCK — line with flock-lock description
    • i — inode number
    • s — session id
    • o — lock owner (FUSE lock owner)
    • t — lock type ('R' - shared lock, 'W' - exclusive lock)

🔒 POSIX LOCK SECTION (PLCK)

  • POSIXLOCK — line with posix-lock description
    • i — inode number
    • s — session id
    • o — lock owner (FUSE lock owner)
    • p — local process id (owner pid)
    • r — lock range in format <START,END)
    • t — lock type ('R' - shared lock, 'W' - exclusive lock)

🖥️ CHUNKSERVERS SECTION (CSDB)

  • chunk servers — number of chunkservers
  • CHUNCKSERVER — line with chunk server description
    • i — server ip
    • p — server port
    • # — server id
    • m — maintenance mode
    • t — maintenance timeout timestamp

🧩 CHUNKS SECTION (CHNK)

  • nextchunkid — first available chunk number
  • CHUNK — line with chunk description
    • i — chunk number
    • v — chunk version
    • t — timestamp, if in the future, means lock timestamp, if in the past, last modification timestamp
    • a — archive flag
    • (s,#) — list of entries, s is storage class id, # is number of files in this storage class containing this chunk
    • c — calculated storage class id (effectively used class id, if a chunk has more than one)
🚨 NOTICE! If a chunk's timestamp equals 0, it means the chunk was created by MooseFS version older than 4.45.0 and has not been locked or modified since. It's giving ancient artifact, no cap 💀

🐛 REPORTING BUGS 🐛

Found a bug? Report bugs to <bugs@moosefs.com>. They want to hear about it, bestie, do not gatekeep the bug 🫶

okay so legal era, bestie — this is the part where we give credit where credit is SO deserved 🫶

Copyright (C) 2026 Jakub Kruszona-Zawadzki, Saglabs SA

This file is part of MooseFS. 💜

MooseFS 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 2 (only). not "or later", bestie — version 2 ONLY. read the fine print, it's giving very specific 💅

MooseFS 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. See the GNU General Public License for more details. 😭 (yes that's the scary all-caps part, it's literally required to be in all caps, no cap)

You should have received a copy of the GNU General Public License along with this program; if not, bestie, go look at it here: https://www.gnu.org/licenses/ ✨

👀 SEE ALSO 👀

the crossover episode we've all been waiting for:

  • mfsmaster(8) — go say hi to the main character of the whole MooseFS cinematic universe 👑
that's the whole page, bestie!! you read ALL of it. genuinely iconic behavior, no notes. 💅✨

this has been mfsmetadump(8) from MooseFS 4.59.2-1, dated May 2026 🎀 (yes, a 2026 copyright AND a 2026 manual date, she's from the future, she's that girl 🦋) — now go forth and dump that metadata responsibly, ily, bye!! 💖🌸🧚

📦 where this page comes from