mdmpd Linux Service
What is mdmpd?
mdmpd Linux service
Monitor MD multipath devices.
Now lets see the manual of mdmpd service.Manual mdmpd:NAME
mdmpd - daemon to monitor MD multipath devicesSYNOPSIS
Enterprise storage requirements often include the desire to have more than one way to talk to a single disk drive
so that in the event of some failure to talk to a disk drive via one controller, the system can automatically
switch to another controller and keep going. This is called multipath disk access. The linux kernel implements
multipath disk access via the software RAID stack known as the md (Multiple Devices) driver. The kernel portion of
the md multipath driver only handles routing I/O requests to the proper device and handling failures on the active
path. It does not try and find out if a path that has previously failed might be working again. That's what this
daemon does. Upon startup, the daemon will fork and place itself in the background. Then it reads the current
state of the md raid arrays, saves that state, and then waits for the kernel to tell it something interesting has
happened. It then wakes up, checks to see if any paths on a multipath device have failed, and if they have then it
starts to poll the failed path once every 15 seconds until it starts working again. Once it starts working again,
the daemon will then add the path back into the multipath md device it was originally part of as a new spare path.OPTIONS
None. This is a very simple program that only does one thing.FILES
If you're using the /proc filesystem, /proc/mdstat lists all active md devices with information about them. mdmpd
requires this to find arrays to monitor paths on and to get notification of interesting events.