Linux "mdmon" Command Line Options and Examples
monitor MD external metadata arrays

Metadata updates: To service metadata update requests a daemon, mdmon, is introduced. Mdmon is tasked with polling the sysfs namespace looking for changes in array_state, sync_action, and per disk state attributes. When a change is detected it calls a per metadata type handler to make modifications to the metadata.


mdmon [--all] [--takeover] [--foreground] CONTAINER

Command Line Options:

Normally, mdmon will fork and continue in the background. Adding this option will skip that step and run mdmon in the fore‐ground.
mdmon --foreground ...
This instructs mdmon to replace any active mdmon which is currently monitoring the array. This is primarily used late in theboot process to replace any mdmon which was started from an initramfs before the root filesystem was mounted. This avoidsholding a reference on that initramfs indefinitely and ensures that the pid and sock files used to communicate with mdmon arein a standard place.
mdmon --takeover ...
This tells mdmon to find any active containers and start monitoring each of them if appropriate. This is normally used with
mdmon --all ...