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NAME | SYNOPSIS | OPTIONS | DESCRIPTION | EXIT CODE | SEE ALSO | COLOPHON |
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E2MMPSTATUS(8) System Manager's Manual E2MMPSTATUS(8)
e2mmpstatus - Check MMP status of an ext4 filesystem
e2mmpstatus [-i] <filesystem>
-i prints out the MMP information rather than check it.
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.
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.
dumpe2fs(8), e2fsck(8), fstab(5), fsck(8),
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
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-10-01.) 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 1.46-WIP March 2020 E2MMPSTATUS(8)
Pages that refer to this page: dumpe2fs(8)
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