man > e2mmpstatus(8)

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📖 NAME

e2mmpstatus — Check MMP status of an ext4 file system

🚀 Quick Reference

Use Case	Command	Description
🛡️ Check if it's safe to mount	e2mmpstatus <device>	Checks MMP status of the ext4 filesystem to prevent multiple mounts.
🔍 Inspect MMP block	e2mmpstatus -i <device>	Prints the current MMP information without performing a safety check.
⚙️ Check by UUID/LABEL	e2mmpstatus UUID=...	Checks MMP status using a filesystem UUID or LABEL instead of a device path.

🔖 SYNOPSIS

e2mmpstatus [-i] <filesystem>

⚙️ OPTIONS

🔹 -i

🖨️ Prints out the MMP information rather than checking it.

📝 DESCRIPTION

e2mmpstatus is used to check Multiple-Mount Protection (MMP) status of an ext4 file system with the mmp feature enabled. The specified file system can be a device name (e.g. /dev/hdc1, /dev/sdb2), or an ext4 file system label or UUID, for example UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root. By default, the e2mmpstatus program checks whether it is safe to mount the file system without taking the risk of mounting it more than once.

MMP (multiple-mount protection) is a feature that adds protection against the file system being modified simultaneously by more than one node. 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.

⏳ 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.

🚪 Exit Codes

✅ 0 ✅ Safe to mount the file system. ❌ 1 ❌ MMP block shows the file system is in use on another node. It is NOT safe to mount. ⚠️ 2 ⚠️ Some other failure occurred that prevents the check from properly detecting the current MMP status.

📚 SEE ALSO

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

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E2fsprogs version 1.46.5 — December 2021 — E2MMPSTATUS(8)

📖 NAME 🚀 Quick Reference 🔖 SYNOPSIS ⚙️ OPTIONS 📝 DESCRIPTION 🚪 Exit Codes 📚 SEE ALSO