e2mmpstatus

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

NAME
       e2mmpstatus - Check MMP status of an ext4 filesystem

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  filesystem  with  the  mmp  feature  enabled.   The  specified
       filesystem  can  be  a  device name (e.g.  /dev/hdc1, /dev/sdb2), or an
       ext4     filesystem      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 filesys-
       tem without taking the risk of mounting it more than once.

       MMP  (multiple-mount  protection)  is  a  feature  that adds protection
       against the filesystem being modified simultaneously by more  than  one
       node.   It  is NOT safe to mount a filesystem when one of the following
       conditions is true:
            1. e2fsck is running on the filesystem.
            2. the filesystem 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
       filesystem, 1 when the MMP block shows the filesystem is in use on  an-
       other  node  and  it is NOT safe to mount the filesystem, 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 1.45.5         January 2020                   E2MMPSTATUS(8)