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 filesystem 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 another 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),