How to check RAID configuration in Linux


I need to check RAID configuration in Linux. How do you check your current software RAID configuration in a Linux-based server powered by RHEL/CentOS or Debian/Ubuntu Linux?

Introduction – Linux supports both software and hardware based RAID devices. This page shows how to check software-based RAID devices created from two or more real block devices (hard drives/partitions).

How to check current RAID configuration in Linux

RAID is an acronym for Redundant Array of Independent Disks. It is nothing but combined single virtual device created from disk drives or partitions. Some RAID levels include redundancy and so can survive some degree of device failure. Linux support following RAID devices:

  1. RAID0 (striping)
  2. RAID1 (mirroring)
  3. RAID4
  4. RAID5
  5. RAID6
  6. RAID10

Check RAID configuration in Linux

The /proc/mdstat is a special file that stores essential information about all presently active RAID devices. Type the following cat command:
cat /etc/mdadm.conf
cat /proc/mdstat
Linux check your current RAID configuration
From the above output, it is clear that I have RAID 10 viraul device made of 5 disk partitions as follows:

  • md125 – RAID device file name
  • active raid10 – RAID type
  • sde3[3] sdb3[2] sdc3[1] sdd3[4] sda3[0] – RAID 10 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

Reviewing RAID configuration in Linux

Want to determine whether a specific device is a RAID device or a component device, run:
# mdadm --query /dev/DEVICE
# mdadm --query /dev/md125
# mdadm --query /dev/md12{5,6,7}

Let us examine a RAID device called /dev/ in more details, execute the following command:
# mdadm --detail /dev/md125
How to check raid configuration in redhat Linux
Finally see info about component device named /dev/sdd3, run:
# mdadm --examine /dev/sdd3
Sample outputs:


See my previous tutorial for more info:

For more information on Linux RAID device, refer to this page.


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