How to check the RAID configuration on Linux/Unix systems

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Linux based systems support both Hardware and Software based RAID systems. So there are times that we want to check the RAID configuration through the operating system. With Linux this is possible to analyze the configuration with the help of mdstat file.

So, to check the RAID configuration you can simply cat the following files;

 

  • cat /etc/mdadm.conf
  • cat /proc/mdstat

Once the above configuration is analyzed, you will end up with the following specific results;

  • md125 – RAID device file name
  • active raid10 – RAID type
  • sde3[3] sdb3[2] sdc3[1] sdd3[4] sda3[0] – RAID device named /dev/md125 made of five partitions (also known as “component device”)
  • [UUUUU] – Shows status of each device of raid member disk/partition. The “U” means the device is healthy and up/running. The “_” means the device is down or damaged

If you want to determine whether a specific device is a RAID device or a component device, you may execute below;

  • mdadm –query /dev/DEVICE
  • mdadm –query /dev/md125
  • mdadm –query /dev/md12{5,6,7}

If you want to see info about component device named /dev/sdd3, run:
Example: # mdadm –examine /dev/sdd3