noble (8) e2mmpstatus.8.gz

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),