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),