GNU/Linux - How to create a NAS on Debian with mdadm, and Samba

Target Architecture

The final architecture looks like this:

Configuration

Hardware Requirements

As shown earlier, it's possible to create a low-cost NAS by recycling old computer hardware.

• Here is an example of hardware configutation:
  • CPU: > intel dual core
  • RAM: 512 MB
  • HDD: 1x 500 GB (OS) + 3x 2TB (data)

Software Configuration

We're going to install Debian on our first hard disk (/dev/sda) and then create a RAID 5 with our three 2TB disks (sdb, sdc and sdd).

Settings

First of all, we need to install Debian, as brilliantly explained here.

Network Configuration

• Edit the /etc/network/interfaces file (replace ens192 by your own interface):

allow-hotplug ens192
iface ens192 inet static
        address 192.168.1.100
        netmask 255.255.255.0
        gateway 192.168.1.254
	dns-nameservers 192.168.1.254

• Restart the system or the networking service:

root@host:~# systemctl restart networking

Partition Table

• Install the gdisk tool, which is the gpt version of fdisk:

root@host:~# apt update && apt install mdadm gdisk

• Clean partition table for /dev/sdb:

root@host:~# wipefs -a /dev/sdb[1-9]*

root@host:~# wipefs -a /dev/sdb

• Create a partition table for /dev/sdb:

root@host:~# gdisk /dev/sdb
GPT fdisk (gdisk) version 1.0.3

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

Creating new GPT entries.

Command (? for help): n
Partition number (1-128, default 1): 
First sector (34-4194270, default = 2048) or {+-}size{KMGTP}: 
Last sector (2048-3907028991, default = 3907028991) or {+-}size{KMGTP}: 
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): FD00
Changed type of partition to 'Linux RAID'

Command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING PARTITIONS!!

Do you want to proceed? (Y/N): Y
OK; writing new GUID partition table (GPT) to /dev/sdb.
The operation has completed successfully.

• Copy the partition table from /dev/sdb to /dev/sdc and /dev/sdd:

root@host:~# sgdisk /dev/sdb -R /dev/sdc

root@host:~# sgdisk /dev/sdb -R /dev/sdd

root@host:~# sfdisk -d /dev/sdb | sfdisk --force /dev/sdc

root@host:~# sfdisk -d /dev/sdb | sfdisk --force /dev/sdd

• Randomize the GUID disk and all partitions to avoid having the same GUID on all disks:

root@host:~# sgdisk -G /dev/sdc

root@host:~# sgdisk -G /dev/sdd

mdadm

mdadm is a utility used to create, manage and monitor software RAID devices on GNU/Linux.

• Install the mdadm tool:

root@host:~# apt install mdadm

• Create a RAID 5 with our three disks:

root@host:~# mdadm --create --level=5 --raid-devices=3 /dev/md0 /dev/sdb1 /dev/sdc1 /dev/sdd1

• Check RAID status:

root@host:~# cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] 
md0 : active raid5 sdd1[3] sdc1[1] sdb1[0]
      418713600 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
      
unused devices: <none>

• Create a file system on /dev/md0:

root@host:~# mkfs.ext4 /dev/md0

• Create a mount folder:

root@host:~# mkdir /data

• Mount the file system located on the /dev/md0 device in the /data directory:

root@host:~# mount /dev/md0 /data

• Show mount points:

root@host:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            983M     0  983M   0% /dev
tmpfs           200M  5.6M  194M   3% /run
/dev/sda2        14G  1.5G   12G  12% /
tmpfs           998M     0  998M   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           998M     0  998M   0% /sys/fs/cgroup
/dev/sda1       511M  3.3M  508M   1% /boot/efi
tmpfs           200M     0  200M   0% /run/user/0
tmpfs           200M     0  200M   0% /run/user/1000
/dev/md0        3.8T   16M  3.7T   1% /data

• Save the RAID configuration so that it is automatically reassembled on system startup:

root@host:~# mdadm --detail --scan >> /etc/mdadm/mdadm.conf

• Update the initramfs to take this into account:

root@host:~# update-initramfs -u

• Add an fstab entry to mount the RAID at startup:

root@host:~# echo "/dev/md0 /data ext4 rw,nofail,relatime,x-systemd.device-timeout=20s,defaults 0 2" >> /etc/fstab

Samba

We're now going to install and configure the samba service, which will enable Windows machines to access file sharing.

• Install the samba service:

root@host:~# apt install samba

• Creating a samba user:

root@host:~# adduser --home /data --system samba

• Set rights:

root@host:~# chown samba: /data

• Create a password to access the share:

root@host:~# smbpasswd -a samba

• Edit the /etc/samba/smb.conf file:

[global]
   workgroup = WORKGROUP
   server string = nas
[share]
   path = /data
   read only = no
   valid users = samba

• Restart samba services:

root@host:~# systemctl restart smbd; systemctl restart nmbd

• From a Windows computer, check that you can access your share: