CentOS / Redhat: Create Software RAID 1 Array

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To create a Software RAID 1 array in CentOS or Redhat, you can follow the steps below:

  1. Identify the disks that you want to use for the RAID array. In this example, we will assume that the disks are named /dev/sda and /dev/sdb.
  2. Partition the disks using the fdisk utility. For each disk, create a primary partition of type “fd” (Linux RAID autodetect) and make it the same size as the other disk’s partition.
  3. Create the RAID array using the mdadm utility. Run the following command to create a RAID 1 array with two disks:
sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1

In this command, “/dev/md0” is the name of the new RAID array, “–level=1” specifies that it should be a RAID 1 array, and “–raid-devices=2” indicates that there will be two disks in the array. Finally, “/dev/sda1” and “/dev/sdb1” are the partitions that will be used for the array.

  1. Format the new RAID array with the desired file system. For example, to format it with ext4:
sudo mkfs.ext4 /dev/md0
  1. Mount the new RAID array to a directory. For example, to mount it to the /data directory:
sudo mkdir /data
sudo mount /dev/md0 /data
  1. Verify that the RAID array is working correctly by checking its status with the mdadm utility:
sudo mdadm --detail /dev/md0

This should show information about the new RAID array, including its status and the disks that are part of it.

  1. Update the /etc/mdadm.conf file to make the RAID array configuration persistent:
sudo mdadm --detail --scan | sudo tee -a /etc/mdadm.conf

This will add a line to the end of the file that specifies the RAID array configuration, so that it will be automatically assembled at boot time.

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