e2mmpstatus(8) — Linux manual page


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

NAME         top

       e2mmpstatus - Check MMP status of an ext4 filesystem

SYNOPSIS         top

       e2mmpstatus [-i] <filesystem>

OPTIONS         top

       -i     prints out the MMP information rather than check it.

DESCRIPTION         top

       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         top

       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         top

       dumpe2fs(8), e2fsck(8), fstab(5), fsck(8),

COLOPHON         top

       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 2020-07-14.
       (At that time, the date of the most recent commit that was found in
       the repository was 2020-03-21.)  If you discover any rendering prob‐
       lems in this HTML version of the page, or you believe there is a bet‐
       ter 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 1.46-WIP       March 2020                   E2MMPSTATUS(8)

Pages that refer to this page: dumpe2fs(8)