HP Serviceguard Extended Distance Cluster for Linux A.01.01 Deployment Guide, Third Edition, May 2008

Managing an MD Device
Viewing the Status of the MD Device
Appendix A106
Viewing the Status of the MD Device
After creating an MD device, you can view its status. By doing so, you
can remain informed of whether the device is clean, up and running, or if
there are any errors.
To view the status of the MD device, run the following command on any
node:
cat /proc/mdstat
Immediately after the MD devices are created and during some recovery
processes, the devices undergo a re-mirroring process. You can view the
progress of this process in the /proc/mdstat file. Following is the output
you will see:
[root@dlhct1 ~]# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sde[2] sdf[0]
9766784 blocks [2/1] [U_]
[=>...................] recovery = 8.9% (871232/9766784) finish=2.7min
speed=54452K/sec
unused devices: <none>
NOTE A status report obtained using the cat /proc/mdstat command shows
the MD device name and the actual device names of the two MD
component devices. It does not show the persistent device names.
After you create an MD device, you can also stop and start the device,
add and remove a mirror component from the MD device.