Before you begin, make sure you have:

• CentOS 7 installed.
• At least two unused hard drives to create the RAID array.
• Access to the terminal with root privileges or via sudo.

1. Install RAID Management Tools

The first step is to install the tools needed for RAID management. CentOS 7 uses mdadm for software RAID management. To install, run the following command in the terminal:

yum install mdadm -y

2. Identify Disks

Before creating the RAID array, identify the disks to be used. Use the lsblk or fdisk -l command to display available disks.

3. Create RAID Array

Depending on your performance and redundancy needs, you can choose different RAID levels. For the purpose of this guide, we'll create a RAID 1, which mirrors data across two disks, ensuring a high level of redundancy.

Run the following command to create a RAID 1 array named md0 from two disks /dev/sdb and /dev/sdc:

mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sdb /dev/sdc

4. Format and Mount RAID Array

After successfully creating the RAID array, format it and mount it to the system. Use ext4 or another filesystem of your choice:

mkfs.ext4 /dev/md0

Then create a mount point and mount the RAID array:

mkdir /mnt/raid1
mount /dev/md0 /mnt/raid1

5. Configure Automatic Mounting at Boot

To automatically mount the RAID array at system boot, add an entry to the /etc/fstab file:

/dev/md0 /mnt/raid1 ext4 defaults 0 0

6. RAID Management and Monitoring

To view the status of the RAID array, use the command mdadm --detail /dev/md0. Regular monitoring of the RAID status is important to detect and address any issues promptly.

7. Backup and Recovery

Although RAID provides a level of data protection, it should not be considered a substitute for regular backups. Ensure that your data is regularly backed up to external storage or a Cloud service.

Software RAID on CentOS 7 offers a flexible and cost-effective solution for improving performance and securing data. With proper configuration and regular monitoring, RAID can significantly contribute to the overall reliability of your system.