60 lines
1.8 KiB
Groff
60 lines
1.8 KiB
Groff
.\" -*- nroff -*-
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.\" This file may be copied under the terms of the GNU Public License.
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.\"
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.TH E2MMPSTATUS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
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.SH NAME
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e2mmpstatus \- Check MMP status of an ext4 filesystem
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.SH SYNOPSIS
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.BR e2mmpstatus " [" \-i ]
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.RI < filesystem >
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.SH OPTIONS
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.TP
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.B \-i
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prints out the MMP information rather than check it.
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.SH DESCRIPTION
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.B e2mmpstatus
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is used to check Multiple-Mount Protection (MMP) status of an ext4
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filesystem with the
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.B mmp
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feature enabled. The specified
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.I filesystem
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can be a device name (e.g.
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.IR /dev/hdc1 ", " /dev/sdb2 ),
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or an ext4 filesystem label or UUID, for example
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.B UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd
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or
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.BR LABEL=root .
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By default, the
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.B e2mmpstatus
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program checks whether it is safe to mount the filesystem without taking
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the risk of mounting it more than once.
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.PP
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MMP (multiple-mount protection) is a feature that adds protection against
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the filesystem being modified simultaneously by more than one node.
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It is NOT safe to mount a filesystem when one of the following conditions
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is true:
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.br
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1. e2fsck is running on the filesystem.
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.br
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2. the filesystem is in use by another node.
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.br
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3. The MMP block is corrupted or cannot be read for some reason.
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.br
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The
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.B e2mmpstatus
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program might wait for some time to see whether the MMP block is being
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updated by any node during this period. The time taken depends on how
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frequently the MMP block is being written by the other node.
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.SH EXIT CODE
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The exit code returned by
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.B e2mmpstatus
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is 0 when it is safe to mount the filesystem, 1 when the MMP block shows
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the filesystem is in use on another node and it is NOT safe to mount
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the filesystem, and 2 if some other failure occurred that prevents the
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check from properly detecting the current MMP status.
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.SH SEE ALSO
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.BR dumpe2fs (8),
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.BR e2fsck (8),
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.BR fstab (5),
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.BR fsck (8),
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