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E2MMPSTATUS(8)                         System Manager's Manual                        E2MMPSTATUS(8)



NAME
       e2mmpstatus - Check MMP status of an ext4 file system

SYNOPSIS
       e2mmpstatus [-i] <filesystem>

OPTIONS
       -i     prints out the MMP information rather than check 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 be‐
       ing  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  up‐
       dated by any node during this period.  The time taken depends on how frequently the MMP block
       is being written by the other node.

EXIT CODE
       The exit code returned by e2mmpstatus is 0 when it is safe to mount the file system,  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, and 2 if some other failure occurred that prevents the check from  properly  de‐
       tecting the current MMP status.

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



E2fsprogs version 1.46.5                    December 2021                             E2MMPSTATUS(8)