e2mmpstatus(8) — Linux manual page

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),

COLOPHON

       This page is part of the e2fsprogs (utilities for ext2/3/4
       filesystems) project.  Information about the project can be found
       at ⟨http://e2fsprogs.sourceforge.net/⟩.  It is not known how to
       report bugs for this man page; if you know, please send a mail to
       man-pages@man7.org.  This page was obtained from the project's
       upstream Git repository
       ⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-05-20.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

E2fsprogs version 1.47.1        May 2024                  E2MMPSTATUS(8)

Pages that refer to this page: dumpe2fs(8)

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