How to do Software Raid 1

Creating a RAID 1 Array

RAID 1 is a type of disk array configuration known as mirroring. RAID 1 uses at least two hard drives to simultaneously copy data onto two disks. This setup enhances data security and allows the system to continue operating even if one of the disks fails.

Key features include:

Mirroring: Each disk in RAID 1 contains an exact copy of the data found on the other disk. In the event of a disk failure, the system can continue functioning using the remaining operational disk.
High Reliability: RAID 1 provides robust resistance against disk failures. When one disk fails, the data on the other disk remains accessible.
Performance Increase: RAID 1 offers a modest performance boost for read operations since data can be accessed simultaneously from two disks. However, write operations may not see a significant performance increase.
Cost: RAID 1 comes with a higher cost for data security because half of the disk space is utilized for redundant backup purposes.

RAID 1 is commonly used in scenarios such as small-scale servers, workstations, or systems where critical data is stored. Its primary purpose is to provide resilience against disk failures and ensure uninterrupted operation.

Let me guide you through creating a software RAID 1 (mirroring) in Linux using the mdadm tool. Here are step by step instructions:

Install mdadm Package:

sudo yum install mdadm

Create RAID 1 Array:

sudo mdadm --create --verbose /dev/md0 --level=mirror --raid-devices=2 /dev/sda1 /dev/sdb1

This command creates a RAID 1 array named /dev/md0 with two devices (/dev/sda1 and /dev/sdb1).

Create File System:

sudo mkfs.ext4 /dev/md0

Add a file system to the created RAID array.

Mount the Array:

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

Mount the RAID array to a directory. You can customize the directory name and mounting point.

Update fstab (Optional):

sudo nano /etc/fstab

Open the /etc/fstab file and add a line like the following:

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

This ensures that the RAID array is automatically mounted on system startup.

Check the Status of the RAID Array:

cat /proc/mdstat

Verify if the RAID array is created and check its status.

These steps provide a general guide for creating a software RAID 1 on Linux. Remember to customize disk names, file systems, and mounting points according to your specific system.