e2mmpstatus

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 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 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  detecting
       the current MMP status.

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

E2fsprogs version 1.46.5         December 2021                  E2MMPSTATUS(8)