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Archive - Create Raid5 with mdadm under Ubuntu

Check current status

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cat /proc/mdstat

Remove curent raid

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sudo umount /dev/md0
sudo mdadm --stop /dev/md0
sudo mdadm --remove /dev/md0

Show existed linux raid

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

Remove superblock

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sudo mdadm --zero-superblock /dev/sda
sudo mdadm --zero-superblock /dev/sdb

Remove partition table

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sudo gdisk /dev/sda
GPT fdisk (gdisk) version 0.8.10

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): x

Expert command (? for help): z
About to wipe out GPT on /dev/sda. Proceed? (Y/N): Y
GPT data structures destroyed! You may now partition the disk using fdisk or
other utilities.
Blank out MBR? (Y/N): Y

Create Raid5

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sudo mdadm --create --verbose /dev/md0 --level=5 --raid-devices=4 /dev/sda /dev/sdb /dev/sdc /dev/sdd

Wait a until end, no restart! Check command: cat /proc/mdstat

Create FileSystem

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sudo mkfs.ext4 -F /dev/md0
sudo mkdir -p /mnt/raid5
sudo mount /dev/md0 /mnt/raid5
echo '/dev/md0 /mnt/raid5 ext4 defaults,nofail,discard 0 0' | sudo tee -a /etc/fstab

Check space

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df -h -x devtmpfs -x tmpfs

Save the Array Layout

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sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf

To available in early boot process

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sudo update-initramfs -u
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