e2mmpstatus (8) - Linux Man Pages
e2mmpstatus: Check MMP status of an ext4 filesystem
NAME
e2mmpstatus - Check MMP status of an ext4 filesystem
SYNOPSIS
e2mmpstatus [-i] <filesystem>OPTIONS
- -i
- prints out the MMP information rather than check it.
DESCRIPTION
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:
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.