Setting up RAID In Linux

I had two 120gb drives, unfortunately, some games are bigger than that and will run much better on a local disk rather than via the ISCSI target. So even with the second drive I was running out of space. RAID to the rescue!

There are a lot of information available online about RAID, but essentially we will be building a RAID 0, which will unify the two drives into a bigger 240gb drive. This will mean, of course, that no data integrity will be guaranteed, and in case of any disk failure, the entire data (240gb) will be lost.

Hardware RAID ?

Let's start by checking if our motherboard supports hardware RAID.

Find out motherboard model.

$ sudo dmidecode -t2

# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 3.1.1 present.

Handle 0x0002, DMI type 2, 15 bytes
Base Board Information
    Manufacturer: ASUSTeK COMPUTER INC.
    Product Name: PRIME B450M-A
    Version: Rev X.0x
    Serial Number: 180731568108548
    Asset Tag: Default string
    Features:
        Board is a hosting board
        Board is replaceable
    Location In Chassis: Default string
    Chassis Handle: 0x0003
    Type: Motherboard
    Contained Object Handles: 0

Check specs for Hardware RAID support:

$ lynx https://www.asus.com/us/Motherboards-Components/Motherboards/PRIME/PRIME-B450M-A/techspec/ -dump | grep -C 2 Raid

   AMD B450 chipset :
   4 x SATA 6Gb/s port(s),
   Support Raid 0, 1, 10
   ...

Onboard hardware RAID! ...wait a minute... no, it's not hardware RAID nor its not fully compatible with linux. It's whats ofter referred as "fake RAID"

Software RAID

We will use mdadm to create a RAID 0.

Find disks

lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT

(...omitted)
sdb    111,8G          disk 
sdc    111,8G          disk 
(...omitted)

Create the Array

$ sudo apt install mdadm
$ sudo mdadm --create --verbose /dev/md0 --level=0 --raid-devices=2 /dev/sdb /dev/sdc

mdadm: chunk size defaults to 512K
mdadm: partition table exists on /dev/sdb
mdadm: partition table exists on /dev/sdb but will be lost or
       meaningless after creating array
mdadm: partition table exists on /dev/sdc
mdadm: partition table exists on /dev/sdc but will be lost or
       meaningless after creating array
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

Verify

$cat /proc mdstat

Personalities : [raid0] 
md0 : active raid0 sdc[1] sdb[0]
    234307584 blocks super 1.2 512k chunks

unused devices: <none>

Format and Automount

$ sudo mkfs.ext4 -F /dev/md0
$ sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf
$ sudo update-initramfs -u
$ mkdir /media/baj0/md0
$ echo '/dev/md0 /media/baj/md0 ext4 defaults,nofail,discard 0 0' | sudo tee -a /etc/fstab