How to upgrade the TerraMaster F4-421 to Unraid with an extra 8GB RAM (12GB total) &  5 drives for the ultimate affordable NAS

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Over the past two years, I have reviewed the superb 10GbE equipped TerraMaster F4-422 and the more affordable TerraMaster F4-421 NAS devices.

TerraMaster, by far, offers the best value for money for the hardware you get. However, the TerraMaster OS isn't to everyone's liking. I have used the TerraMaster F4-422 with its TOS for over a year as my NAS and have had no major problems with it, but the system is a bit clunky and lacking features compared to the likes of Synology.

Recently, I have been flirting with the idea of upgrading my primary AMD Ryzen powered server to Unraid or Freenas from Ubuntu Server and realised that TerraMaster NAS devices were easily upgraded to different operating systems.

I originally used Ubunutu server because I had hosting servers that used this, and it made sense to have a system at home that I could experiment with. However, by all accounts, both TrueNas and UnRaid are far more user friendly for home users, and they have the ability to run VMs should you wish to play with a full OS.

The internals of the TerraMaster is just like a normal PC, similar to an Intel NUC. The OS runs off an internal USB drive, and you have full access to the BIOS.

Before committing to upgrading my main server to a new NAS orientated OS, I figured I would upgrade both my TerraMaster units. The TerraMaster F4-421 is now running UnRaid, while the TerraMaster F4-422 is running TrueNas Core.

I will separate this into two posts, one for each NAS and OS, but a lot of the content will be the same.

TerraMaster F5 / F4-422 vs TerraMaster F4-421

There is only one big difference between these units, the F4-422 has a 10Gbit Ethernet port plus two additional Gig Ethernet ports, and the F4-421 has just two Gigabit ports.

The HDMI port of the TerraMaster F4-422 is blocked off, but the actual HDMI port is still there, once you take the back off, you have easy access, and you can pop the HDMI tab out.

At the time of writing, TerraMaster don't appear to be selling the TerraMaster F4-422, it is just the two, five or eight-bay models. There is currently a £110 price difference between the F4-421 and F5-422.

An alternative option is the affordable TerraMaster F5-221 listed on Amazon this has 2GB of RAM and Intel Apollo J3355 2.0GHz dual-core CPU plus the extra 5th drive caddy. The performance will obviously be lower, but I expect it is fine for a basic UnRaid NAS.

Hidden 5th SATA port for a 5-drive NAS

If you have a four-bay TerraMaster, you will be pleased to find out that the internal hardware is identical to the 5-bay variants. They have just blocked off the 5th bay drive tray.

Some people have modded their NAS to add on a 5th tray. For me, I used an SSD in the 5th slot for the cache. With the NAS fully populated, the SSD and the SSD just hanging there, there is only a few mm wobble before it toucher the 4th drive

If you are reckless, you could leave the SSD just hanging there, which is what I have done temporarily. I expect I will make some sort of support and likely stick it to the hard drive it sits next to.

You can buy a TerraMaster drive tray for £30, so you could mod the entire NAS for it to fit in, or possibly hacksaw off the front of the tray and slide it in with the front panel removed.

Terramaster Hard Drive Tray For NAS models F2/F4/F5 DAS...
  • Original hard drive tray from TerraMaster.
  • Compatible with NAS series models of F2-220,...
  • Compatible with DAS series models of D2-310,...
  • Compatible with 3.5” SATA hard drive, 2.5”...

TrueNas vs UnRaid

I have never used UnRaid or TrueNas Core before, I think I was only aware of them from Reddit and only knew roughly what they did. So I may not be the best person to compare.

For a start, TrueNas core is BSD based UnRaid, whereas UnRaid is based on Linux Slackware.

UnRaid requires a paid licence which is $59 for up to 6-storage drives.  

From my very brief experience, UnRaid is probably the best option if you want something simple to set up, both in terms of hardware and the OS. You can mix and match drive sizes, and you can also expand the system easily with new drives. This makes it better for people like me that have slowly bodged together a system over the years with a mix of drives.

With the Community Application plugin, UnRaid also has a wider range of easy to install applications, and it has Docker built-in natively.

On the other hand, if you are building a server from scratch with matching sized drives, then TrueNas is perhaps preferable due to improved performance. Using the ZFS file system, data will be stripped and written to multiple drives simultaneously. You can also run the equivalent of RAID10, giving you significantly better performance. While Docker is not natively supported, under the Plugins section, you have all the applications most home users could want, including Plex, NZBGet, NextCloud etc. TrueNas Scale does support Docker, but I believe that it is still in Beta.


Inside the TerraMaster F4-421 is a small USB drive. You could install the new OS on this drive, but considering how cheap drives are, you may as well keep it as a backup and replace it with a newer drive.

It needs to be a very short drive as there is not much clearance.

I had issues getting the UnRaid installer to work properly, so I had to do the manual install, and the instructions say this is limited to to 32GB drives.

The option I went for is the SanDisk Ultra Fit 32 GB USB 3.1 Flash Drive (SDCZ430-032G-G46), which cost a princely sum of £8.

I am not sure if choosing the USB 3.1 version will make any difference with performance, but it's so cheap I don't really care.

SanDisk SDCZ430-032G-G46 Ultra Fit 32 GB USB 3.1 Flash Drive...
  • A compact, plug-and-stay, high-speed USB 3.1 flash...
  • Simple, fast way to add up to 256GB of storage to...
  • Read speeds up to 130MB/s
  • Write up to 15x faster than standard USB 2.0...

Opening Up the TerraMaster F4-421

Opening up the box is very easy, you will need some electronics screwdrivers.

When you pull the rear panel away, be careful as the fans are plugged in with relatively short cables. The motherboard and, therefore two fan headers run down the side with the LEDs on the top edge. They are just behind the HDMI port and can be easily unclipped.

You should then be able to slide the main part of the body off.

Upgrading the RAM

Upgrading the RAM is very easy. For this drive, I have temporarily stolen some DDR3 RAM from an old laptop, upgrading it with an additional 4GB RAM.

For the TerraMaster F4-422 I bought some random brand 8GB DDR3 RAM and used that. While TerraMaster state that these drives can only go to 8GB (4 GB + 4 GB) my TrueNas installation recognises and uses 12GB. I assume the same will apply to UnRaid and the TerraMaster F4-421.

You probably should take the full front panel off to upgrade the RAM, but I am lazy, I unscrewed the top two screws, and this gave enough wiggle room to slot the RAM in.

Installing UnRaid

I had some issues at first, mostly user error, as I obviously haven't read the instructions.

I assumed the UnRaid installation would be like other OS installs, you copy the OS to a bootable USB, and it installs the OS on the chosen drive.

However, you install the actual OS to the USB drive, and it just boots straight from that.

I also had an issue with the UnRaid USB Creator. For whatever reason, I couldn't get the TerraMaster to recognise the drive as a boot drive. I tried changing drive priorities in the BIOS, but no luck.

Then, I realised the manual install says you can only use a 32GB USB drive, and I had bought 64GB.

Anyway, once my new drive arrived, I followed the manual install instructions, which includes:

  • Format the device using the FAT32 file system. It must not be ex-FAT or NTFS.
  • Set the ‘volume label' to UNRAID (case-sensitive, use all caps).
  • Copy the files over (downloaded and unzipped from UnRaid)
  • I did not change the EFI- director for UEFI boot
  • For modern Windows PCs, you need to right click on the make_bootable file, run as admin, then hit enter twice following the instructions from CMD.

I found that you can just about slide out the existing USB without unscrewing the cage from the motherboard, so you just need to swap over the old TerraMaster USB with the new one.

That's it, UnRaid should boot up, I didnt need to make any changes in the BIOS for it to boot. If you have the NAS plugged into a monitor, you will be informed of the IP address. Or you can just search for it on your network with something like Advanced IP Scanner.

Assuming you haven't bought a licence yet, you can use UnRaid free for a month while you try things out.

Setting up your Array with Cache and Parity

I have used old knackered drives for this test set-up. My parity drive has multiple SMART errors, so I will be replacing it as soon as possible. None of the data on this NAS is important.

This bit was nice and easy, less confusing than TrueNas, though neither is particularily hard.

Select the drives you want in your main array, then select the parity drive. The Parity drive should be the same size as the largest disk in the array.

You can also add a cache drive by going to pool devices and selecting the installed SSD.

If the drives were already in a format UnRaid can read, I think all your data should be retained. In my case, I had to format the drives.

Once formatted, the array will be immediately available, but the parity drive needs to be built, and your data will be at risk until this drive is fully built. For my system, a 4TB drive takes about 8 hours.

How to install Apps – NextCloud / NZBGet / Radarr / Sonarr / Torrents

As I hadn't read up that much about UnRaid, it wasn't immediately obvious how to install apps easily. Docker is built into the system natively, but if you want to add a container via the Docker menu, you have to set everything up manually.

There are some repositories of templates that significantly simpify things, but the easiest option by far is to install the Community Applications plugin.

A full thread is available here

Installation couldn't be easier.

As the name suggests, this is a community-run app database, so you can't always guarantee the quality, but I haven't had any problems yet. Each application states the repository used, linuxserver is always a safe bet, but many others are excellent too

When you select to install an application, you can install the default, latest or beta/testing versions. It will then load up all the container information for you. Generally, all you need to do is define the path you would like to use.

Installation takes a few seconds normally and is considerably faster than FreeNas installations.

Then, from the main dashboard, you can see all your docker containers with various options, including starting and stopping them. Alternatively, you can manage things via the Docker menu. Setting up autostart for certain apps would be a good idea.

From my limited experience, the whole process is much more user friendly than the default TerraMaster OS and with more applications. It's the closest you are going to get to Synology.


Call me an UnRaid convert. I love the simplicity of the system, and the community app plugin makes setting new Docker containers far easier than Docker Compose or the TOS docker application.

Drive performance isn't amazing, and in my case, this is made worse by old problematic drives, but overall it is adequate for your average users. Certainly, enough for all your downloading/streaming needs as well as backups.

Being able to upgrade a TerraMaster NAS to UnRaid significantly improves their overall appeal. They were decent to start thanks to the affordable pricing compared to other brands. Now with UnRaid, you can have something with significantly improved functionality giving you something close to a budget Synology.

One caveat I should point out, the two TerraMaster systems I have upgraded are the Intel-based units, some of the cheaper models are based on ARM, and I am not sure how easy they are to upgrade to UnRaid/TrueNas

Last update on 2022-05-23 / Affiliate links / Images from Amazon Product Advertising API

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