I am trying to build a RAID 6 array using MDADM (I want to use it as NAS to synchronize files between other devices). My setup consists of a Raspberry Pi 3B with 4 256GB USB drives plugged directly into the 4 USB ports.

It all works fine up to the last step of mounting the partition, where I got (so far) 3 different types of errors:

  1. segmentation fault
  2. mount: /mnt/raid: wrong fs type, bad option, bad superblock on /dev/md127p1, missing codepage or helper program, or other error.
  3. the command just doesn‘t terminate, even if I leave it running overnight.

Am I doing anything fundamentally wrong?

Here are the commands that I use:

apt-get upgrade

sudo apt-get install mdadm

sudo mkdir -p /dev/md
sudo mkdir -p /mnt/raid
sudo chown -R pi:pi /mnt/raid

sudo mdadm --create --verbose /dev/md/raid6 --level=6 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

sudo fdisk /dev/md/raid6 (going to defaults in all prompts and then pressing „w“ to write in the end)

sudo mkfs.ext4 -v -m .01 -b 4096 -E stride=128,stripe-width=256 /dev/md/raid6p1

sudo mount /dev/md/raid6p1 /mnt/raid

I‘m new to Linux, so I would appreciate answers at beginner level.

1 Answer 1


My setup consists of a raspberry pi 3B with 4 256GB USB drives plugged directly into the 4 USB ports.

I'm fairly certain that the Raspberry Pi 3B cannot direct power four USB drives. So the first step to solve your problem is to use a powered USB hub.

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