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NAS - using a thin client and a USB hard drive

Last modifications: 24 May 2021

• What is NAS?
• Why making my own NAS?
• The hardware
• Preparations for installation
• Installing GNU/Linux
• Mounting the external hard drive
• Get access to your NAS
• Multi-room audio player
• Network printing
• Downloading torrents
• World wide access (in the cloud!)
• Spinning down the hard drive(s)
• Conclusion

What is NAS?

Network attached storage (NAS) is data storage connected to a network, providing data access to a all the computers in this network. A NAS device actually is a computer as well but without monitor, keyboard and mouse. It operates as a file server and normally runs 24/7. The image below shows how a NAS device and multiple computers are connected to a home network (LAN).

With NAS there is no need to have copies of the same files on different computers. At home for example, everybody can view the same holiday pictures stored on the NAS device, using their own computer. Most NAS devices can do more, for example function as a music player or a print server. With a print server, every computer at home can print to the printer connected to the NAS device.

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Why making my own NAS?

Many NAS home consumer devices run a customised version of GNU/Linux. That may sound great if you are a GNU/Linux fan (like me) but...

• Controlling the device is often limited to some configurable preferences.
• Usually it is not possible to run programs other than the preinstalled ones.
• Connecting to a NAS device using SSH or Telnet is not always possible.
• If it is, chances are you can not use all the shell commands you are used to.

It made me think: why not install the GNU/Linux flavour I want, install the software I want and configure the NAS device the way I want?

Unfortunately most NAS devices do not allow the installation of other operating systems or can not run a "standard" GNU/Linux distribution.

So I decided to make my own NAS. Just to be in control. Just for fun. And during this project I learned some more about GNU/Linux as well.

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The hardware

To make your own NAS, you need a computer with a network adapter and enough disk space for all your data. Of course you also need an operating system and programs to run on it. But first let's focus on the hardware.

Why using a thin client?

You could use a normal PC as a NAS. But the energy consumption of a PC is quite high and I find that undesirable for a device that is running day and night. Two other things I do not like about the PC option are noise and size.

Computers that do not have these disadvantages are thin clients. They are small, do not make any noise (no fans) and energy consumption is low. Yet they can be very powerful. Thin clients do not have an internal hard drive but USB hard drives can easily be connected.

The hardware I use

So I needed a thin client and a USB hard drive. I found the following hardware for my NAS device:

• Thin client: HP t610 (second hand)
• USB hard drive: Samsung T5 SSD (500 GB)

Here some specifications of the HP t610:

• AMD Dual-Core 1.65 GHz processor
• 1.4 GB RAM
• 13 GB flash
• 4x USB 2.0 and 2x USB 3.0 ports
• Ethernet 10/100/1000 Mb/s (RJ-45)

These specifications are more than sufficient for the things I want to do with my NAS.

The hard drive I chose is a Solid State Drive, the Samsung T5. This SSD gets its power via USB, so no external power supply is needed. It is energy efficient and fast (USB 3.1). Nowadays many affordable USB hard drives are available.

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Preparations for installation

Before you can install GNU/Linux on your thin client, you have to do some preparations first.

Hooking up the thin client

Connect a monitor and keyboard to your thin client. Monitor and keyboard will only be used during installation. Furthermore you need to connect your thin client to the internet and of course to a power supply...

Downloading GNU/Linux

Iso images of GNU/Linux installers can be found online. I chose to use the Debian network installation.

Making a bootable USB stick

The most convenient way to install GNU/Linux is from a USB stick (if you want to install from disc, you need to connect an external CD/DVD player to your thin client). To make a bootable USB stick, you can not just copy an iso image to it. You need a special tool to do it.

Booting from USB stick

In order to run the installer, the thin client has to boot from the USB stick. You can set this in the boot menu. If a boot menu is not available, you have to change the boot order in the BIOS.

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Installing GNU/Linux

I installed Debian GNU/Linux on the internal flash drive of the thin client. On a NAS device you do not need a graphical desktop environment, so I only installed the standard system utilities. In my setup, the complete system (OS and applications) uses about 4 GB hard disk space.

If the flash drive of your thin client is not big enough, you can install the operating system on the external USB hard drive. Or you can install it on a second USB hard drive or USB stick (if you prefer to have a separate system disk).

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Mounting the external hard drive

In a desktop environment you can easily mount and access an external hard drive with a mouse click. On a server it is convenient to mount the external hard drive automatically.

Note: If you installed GNU/Linux on the external hard drive, the drive will already be mounted automatically. So in this case you can skip the how-to below.

# blkid

UUID=uuid-of-drive-partition /mount/directory ext4 noauto,x-systemd.automount 0 2

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Get access to your NAS

Now that your NAS is up and running, it is time to enable remote access from another computer.

Access with SSH

The first thing to install is the OpenSSH server. After installation, check if you can log on to your NAS from a remote terminal using SSH. If this works fine, you can remove the monitor and the keyboard. From now on, you will have to control your headless NAS via a terminal on another computer.

Access with a file manager

To access your NAS using a file manager on a remote GNU/Linux computer, install the OpenSSH SFTP server. If you want to access your NAS with a Windows computer using the Windows file manager, install Samba.

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Multi-room audio player

My complete music collection is stored on my NAS. The music can be streamed to other computers, all playing in sync. A multi-room audio system makes this possible.

Read more about my other project: Multi-room audio player.

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Network printing

My printer is connected to my NAS, so I can print from any computer in my home network. To install and manage printers I use the CUPS web interface. By default you can use this web interface only on the computer where CUPS is installed (via: http://localhost:631). But it is possible to enable remote access to CUPS.

   ...
   
   # Only listen for connections from the local machine.
   Port 631 # was: Listen localhost:631
   Listen /var/run/cups/cups.sock

   ...
   
   # Web interface setting...
   WebInterface Yes

   # Restrict access to the server...
   <Location />
     Order allow,deny
     Allow all
   </Location>
   
   # Restrict access to the admin pages...
   <Location /admin>
     Order allow,deny
     Allow all
   </Location>

  # Restrict access to configuration files...
   <Location /admin/conf>
     AuthType Default
     Require user @SYSTEM
     Order allow,deny
     Allow all
   </Location>

   ...

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Downloading torrents

Transmission is a nice torrent client for downloading and sharing large files, like software, movies and music. But it took me some time to find out which parts to use on my NAS device.

When Transmission is up/downloading, this will slow down other internet traffic. Therefore on my NAS device Transmission is only active at night. I use transmission-remote and cron to schedule this.

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World wide access (in the cloud!)

It can be very practical to have world wide access to your data. So put your NAS in the cloud! Here three ideas using the Apache web server.

World wide access (read only)

Normally Apache is used to serve web pages over the Internet. I use Apache to serve the data on my NAS, so I can easily access my data world wide using a web browser (see the image below).

World wide access with WebDAV (read and write)

Write access to my NAS from the Internet is restricted to a specific directory. This directory is accessible using the WebDAV protocol (supported by Apache and other web servers).

A WebDAV client is needed to access the directory share. You may use a special WebDAV client application or a file manager with built in support for WebDAV.

Share data with others

A public accessible directory in your web server setup can serve as a place to share large files with others. Just like with WeTransfer, you only send a link to the recipient, not the data itself. I call it MeTransfer. Very handy!

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Spinning down the hard drive(s)

Spinning down a hard drive may improve its lifetime. Although my internal flash drive and external SDD can not be spun down, the number of writes can be reduced. The term "spinning down" will be used here to indicate the reduction of disk writes, in general.

I found out that some processes are writing to disk quite often:

• rsyslogd
• kjournald
• cron
• exim4

Using laptop mode

From the Debian website: laptop mode is a Linux kernel feature that allows your laptop to save considerable power, by allowing the hard drive to spin down for longer periods of time. This feature is also suitable for spinning down the hard disks of a server (read the note below). If you want to use laptop mode, you need to install the package Laptop Mode Tools.

   ENABLE_LAPTOP_MODE_TOOLS=1
   ENABLE_LAPTOP_MODE_ON_AC=1
   LM_AC_MAX_LOST_WORK_SECONDS=7200
   LM_AC_HD_IDLE_TIMEOUT_SECONDS=20

Problems with readahead

In laptop mode readahead is enabled by default. Reading ahead means that whenever some data is read from disk, the data which is most likely to be accessed next is read as well, ahead of time.

In my case readahead caused two problems:

• Video played from my NAS was distorted for a short while at certain moments (I think at the moments a new readahead was done).
• My NAS responded slowly to simple terminal commands like "ls" (I think readahead reads more than only the command executable you need).

Disabling readahead solved these problems.

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Conclusion

When I started my NAS project I had no idea what the result would be...

Version 1.0

In December 2011 I started with my NAS project, using a single core thin client and an external "old fashion" hard drive. Although this set up only had USB 2.0 and a 100 Mb/s network connection, it worked very well.

Speed was not sublime, but is was enough. For example, watching video from my first NAS worked smoothly, without hick-ups. It has been running day and night for about 8 years without any problem.

Current version

In January 2020 I decided to speed up things, implementing the set up as described on this page. With a dual core processor, an SSD via USB 3.0 and a 1 Gb/s network connection, this new set up is really fast and ready for the future!

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