In this hands-on lab, we will create partitions on additional drives so we can build a software RAID. Once we have a mirror configured and operating, we will fail a drive and remove it from the array, add a new drive to the array, and rebuild the mirror. This is a common set of tasks in the enterprise, as RAID mirrors are used for fault tolerance to prevent data loss due to drive failure.
Learning Objectives
Successfully complete this lab by achieving the following learning objectives:
- Provision the Disks with a Primary Partition So They Can Be Added to the RAID rray
Get the names of the drives with no partitions
lsblkYour output should match the below (the drives you’ll be using later are
nvme0n1,nvme1n1, andnvme2n1):NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT nvme0n1 259:0 0 2G 0 disk nvme1n1 259:1 0 2G 0 disk nvme2n1 259:2 0 2G 0 disk nvme3n1 259:3 0 10G 0 disk ├─nvme3n1p1 259:4 0 2M 0 part ├─nvme3n1p2 259:5 0 20M 0 part /boot/efi └─nvme3n1p3 259:6 0 10G 0 part /Create partitions on the drives, performing the following for each drive:
sudo fdisk /dev/nvme0n1 Then press n for new Then press p for primary Then press 1 for the partition number Then enter for starting/first sector Then enter for ending/last sector Then w to write the changesPrompt the kernel to reread the partition table for the drive:
sudo partprobe /dev/nvme0n1Repeat the steps for all three drives.
- Verify mdadm Is Installed and Create a RAID 1 (`/dev/md0`) from Two of the Drives
Verify that mdadm is installed:
rpm -q mdadmCreate the RAID 1 using two of the drives:
sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/nvme0n1p1 /dev/nvme1n1p1Watch it being created:
sudo watch cat /proc/mdstatHit Ctrl+C to quit.
Now the array is complete, check the status:
sudo mdadm --detail /dev/md0
- Create an XFS Filesystem on the Array and Mount It to `/mnt/raid1`
Create the filesystem:
sudo mkfs.xfs /dev/md0Create a directory and then mount the RAID volume into the directory:
sudo mkdir /mnt/raid1 sudo mount /dev/md0 /mnt/raid1Verify the RAID size is correct and the mount displays:
lsblkNote that your array is shown in the output, including the mount point:
nvme0n1 259:0 0 2G 0 disk └─nvme0n1p1 259:9 0 2G 0 part └─md0 9:0 0 2G 0 raid1 /mnt/raid1 nvme1n1 259:1 0 2G 0 disk └─nvme1n1p1 259:10 0 2G 0 part └─md0 9:0 0 2G 0 raid1 /mnt/raid1 nvme2n1 259:2 0 2G 0 disk └─nvme2n1p1 259:7 0 2G 0 part nvme3n1 259:3 0 10G 0 disk ├─nvme3n1p1 259:4 0 2M 0 part ├─nvme3n1p2 259:5 0 20M 0 part /boot/efi └─nvme3n1p3 259:6 0 10G 0 part /
- Compress `/var/log/messages` Using `tar` and Place It in the `/mnt/raid1` Directory
Compress the
messagesfile, and place it in the newly createdraid1directory:sudo tar -czvf /mnt/raid1/messages.tar.gz /var/log/messagesVerify the data is in place and the file is not empty:
ls -l /mnt/raid1
- Simulate a Failure of One of the Drives and Then Remove It from the Array
Set one drive to faulty:
sudo mdadm --manage --set-faulty /dev/md0 /dev/nvme1n1p1Confirm that the drive is in a faulty state:
sudo mdadm --detail /dev/md0Remove the faulty drive from the array:
sudo mdadm --manage --remove /dev/md0 /dev/nvme1n1p1Confirm that the drive has been removed:
sudo mdadm --detail /dev/md0
- Add the Third Drive to the Array, Let It Rebuild, and Verify the Data Is in Place
Add the drive to the array:
sudo mdadm --manage --add /dev/md0 /dev/nvme2n1p1Watch the rebuild:
sudo watch cat /proc/mdstatHit Ctrl+C to quit.
Once the rebuild is complete, confirm that the array shows all drives synced:
sudo mdadm --detail /dev/md0Confirm that the data is still present:
ls -l /mnt/raid1
- Add the Unused Disk Back to the Array as a Spare in Case of Another Failure
Re-add the failed drive back to the array as a spare:
lsblkNote the
nvme1n1p1partition is not currently linked to the array — that’s the one to add back in:NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT nvme0n1 259:0 0 2G 0 disk └─nvme0n1p1 259:9 0 2G 0 part └─md0 9:0 0 2G 0 raid1 /mnt/raid1 nvme1n1 259:1 0 2G 0 disk └─nvme1n1p1 259:10 0 2G 0 part nvme2n1 259:2 0 2G 0 disk └─nvme2n1p1 259:7 0 2G 0 part └─md0 9:0 0 2G 0 raid1 /mnt/raid1 nvme3n1 259:3 0 10G 0 disk ├─nvme3n1p1 259:4 0 2M 0 part ├─nvme3n1p2 259:5 0 20M 0 part /boot/efi └─nvme3n1p3 259:6 0 10G 0 part /Add the drive to the array as a spare:
sudo mdadm --manage /dev/md0 --add /dev/nvme1n1p1The resulting output should be:
mdadm: added /dev/nvme1n1p1Verify that the drive is added to the array as a spare:
sudo mdadm --detail /dev/md0
