1E2MMPSTATUS(8) System Manager's Manual E2MMPSTATUS(8)
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6 e2mmpstatus - Check MMP status of an ext4 filesystem
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9 e2mmpstatus [-i] <filesystem>
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12 -i prints out the MMP information rather than check it.
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15 e2mmpstatus is used to check Multiple-Mount Protection (MMP) status of
16 an ext4 filesystem with the mmp feature enabled. The specified
17 filesystem can be a device name (e.g. /dev/hdc1, /dev/sdb2), or an
18 ext4 filesystem label or UUID, for example
19 UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root. By default,
20 the e2mmpstatus program checks whether it is safe to mount the filesysâ
21 tem without taking the risk of mounting it more than once.
22 MMP (multiple-mount protection) is a feature that adds protection
24 against the filesystem being modified simultaneously by more than one
25 node. It is NOT safe to mount a filesystem when one of the following
26 conditions is true:
27 1. e2fsck is running on the filesystem.
28 2. the filesystem is in use by another node.
29 3. The MMP block is corrupted or cannot be read for some reason.
30 The e2mmpstatus program might wait for some time to see whether the MMP
31 block is being updated by any node during this period. The time taken
32 depends on how frequently the MMP block is being written by the other
33 node.
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36 The exit code returned by e2mmpstatus is 0 when it is safe to mount the
37 filesystem, 1 when the MMP block shows the filesystem is in use on
38 another node and it is NOT safe to mount the filesystem, and 2 if some
39 other failure occurred that prevents the check from properly detecting
40 the current MMP status.
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43 dumpe2fs(8), e2fsck(8), fstab(5), fsck(8),
44E2fsprogs version 1.45.6 March 2020 E2MMPSTATUS(8)