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 email@example.com. This page was obtained from the project's upstream Git repository ⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on 2020-06-09. (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 firstname.lastname@example.org E2fsprogs version 1.46-WIP March 2020 E2MMPSTATUS(8)
Pages that refer to this page: dumpe2fs(8)