E2MMPSTATUS(8)

📦
version 1.47.4 · 6 versions
, in alpine 3.24, arch rolling, nixpkgs unstable, ubuntu stonking

💅 E2MMPSTATUS — bestie's guide to checking MMP status (section 8, system manager's manual energy)

okay so picture this: you're about to mount an ext4 file system and you just need to know if it's already living its best life on some other node. that's literally what e2mmpstatus is for, bestie. it's the vibe check for Multiple-Mount Protection. 🦋

✨ SYNOPSIS ✨

e2mmpstatus [-i] <filesystem>

🌸 OPTIONS 🌸

  • -i — instead of doing the whole check thing, it just prints out the MMP information. like, show me the receipts, don't judge me. 👑

💖 DESCRIPTION 💖

e2mmpstatus is what you use to check the Multiple-Mount Protection (MMP) status of an ext4 file system that has the mmp feature enabled. no cap.

and the filesystem you hand it? so flexible of it, honestly. it can be:

  • a device name, e.g. /dev/hdc1, /dev/sdb2
  • an ext4 file system label, like LABEL=root
  • or a UUID, for example UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd

by default, e2mmpstatus checks whether it's safe to mount the file system — like, without taking the risk of mounting it more than once. main character safety energy. 🫶

🧚 what even is MMP though

MMP (multiple-mount protection) is a feature that adds protection against the file system being modified simultaneously by more than one node. it's giving "please, one at a time, we're not doing a group project." 😭

it is NOT safe to mount a file system when one of the following conditions is true: 1. e2fsck is running on the file system. 2. the file system is in use by another node. 3. The MMP block is corrupted or cannot be read for some reason.

also heads up: the e2mmpstatus program might wait for some time to see whether the MMP block is being updated by any node during this period. the time taken depends on how frequently the MMP block is being written by the other node. so yeah, it might be standing there staring at the block like 👀 — depends entirely on how chatty the other node is.

🔥 EXIT CODE 🔥

the exit code returned by e2mmpstatus is:

  • 0 — when it is safe to mount the file system ✅ slay
  • 1 — when the MMP block shows the file system is in use on another node and it is NOT safe to mount the file system 💀 do not
  • 2 — if some other failure occurred that prevents the check from properly detecting the current MMP status 🙈 mystery behaviour, not iconic

👑 SEE ALSO 👑

dumpe2fs(8), e2fsck(8), fstab(5), fsck(8),

this has been E2fsprogs version 1.47.4, March 2025 — ty for coming to my ted talk, go check your MMP block before you mount anything, ily, bye 💜✨🎀

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