The TerraMaster T6-423 is supposed to be a much more advanced NAS server compared to the previous F2-223. Among other things, it has six drive bays and two NVMe slots, rivaling the DS1621+, Synology's latest consumer-grade server of the same capacity.
But the extra drive bays are exactly this new server's downfall. They reveal its design flaw and the bugginess of TerraMaster's latest NAS operating system, the TOS version 5. The software is not ready to handle the many implied storage options.
As a result, while I recommended the F2-223, the T6-423 proved unbearable in my testing.
Here's the bottom line: If you're looking for a relatively low-cost, high-capacity, Mulit-Gig-ready server and intend to use it as a simple network storage space, the new server will work out and is even worth its friendly price tag of $700 (diskless). But avoid it at all costs if you want anything more. Go with a Synology instead.
Dong's note: I updated this post on January 26, 2023, to add information about the server's two M.2 NVMe slots which were originally overlooked and erroneously omitted.
TerraMaster T6-423: A flawed NAS server
The T6-423 is the first high-capacity server from TerraMaster I've tested. With six drive bays, by design, it can handle all more advanced RAID configurations instead of only RAID 1 and RAID 0 in the case of a Dual-bay counterpart.
I was excited to try all that out and ran into one disappointment after another, starting with the server's physical design.
But first, it's worth noting that the new server runs TerraMaster's latest NAS operating system, TOS 5, and is generally the same as any other server running the same OS in terms of the setup process, interface, settings, and app. Overall, TOS 5 is a streamlined experience.
If you're unfamiliar with TerraMaster, open the drawer below for some generally positive highlights of the relatively new OS version.
TerraMaster TOS 5 in brief
This portion of the extra content is common among TerraMaster servers.
Simple OS setup process
To make a TerraMaster server work, you'd first need to install the operating system, TOS 5, which is a simple process.
First, download and install the TNAS PC software — there are Windows, macOS, and Linux versions — on a computer and run it.
After a few seconds, the software will find the server in the network, as shown in the screenshots above. Now you can use its IP address on a browser or click on the software's login button, to launch the web-based setup wizard.
The wizard will work through a few self-explanatory steps to install the OS — directly from TerraMaster's server or via a local file — and everything else, including picking the RAID configurations, file format (BTRFS or EXT4), and the first user account.
You can start using a server with a single drive. But to use any RAID, you must have two or more. Generally, the setup process only allows for creating a single storage pool. To have more pools, when applicable, you need to use the Storage Manager — part of the Control Panel — once the server is up and running.
Depending on your Internet speed, the process will take between five to 30 minutes. And then, you can log in to the server's web interface — via the same IP address — to further customize it.
Robust web interface, flexible TRAID, and LDAP support
Unlike the clunky TOS 4.x, TerraMaster's TOS 5 is robust, similar to Synology DSM, and has a web-based user interface resembling a native operating system.
You can run multiple apps simultaneously and use the Control Panel to configure the router. Most importantly, there's the app store, called App Center, that allows for installing more apps on the server.
TRAID allows for mixing drives of different capacities, easy storage scale-up, and automatic RAID function — you automatically get something similar to RAID 1 when using two drives, RAID-5 with three or more, etc. — with a slight performance sacrifice.
In any case, the support for TRAID shortens the gap that TerraMaster trails behind Synology considerably in terms of storage management.
Another noteworthy feature is TOS 5 now supports domain/LDAP integration, allowing the server to work as part of a business environment with a domain controller. This feature is a must-have if TerraMaster wants to break into the business environment.
Few useful apps
Apps are where a server shows its power, and it's the area TOS is still much behind DSM.
First, it's the quantity. There are only 55 apps (44 if you take out the Betas — the numbers will change over time). Among these, only a few are useful. The rest are largely irrelevant to general users, and there are no real apps for business users.
For comparison, Synology has over a hundred well-designed apps for all business and home categories.
That said, I found the following apps significant compared to the previous version of TOS.
- Snapshot: Similar to Snapshot and Replication of Synology, TerraMaster's Snapshot — available only when you use the BTRFS file system — enables the keeping of versions in shared folders to fight against accidental deletions or alterations. It also supports a replication feature to keep a copy of a shared folder in real time.
- Transmission: An app for download, similar to the Download Station of Synology. This app allows users to download BitTorrent files without having to have a PC on, but unfortunately, it has no search function, which is a huge shortcoming, and it doesn't work with other types of downloads, such as FPT or HTTP.
- Multimedia Server: A server app for streaming content hosted on a TerraMaster server, similar to the Media Station of Synology. TerraMaster doesn't have playback apps on the front end, but Multimedia Server supports standard streaming protocols — you can use third-party streamers with it. On top of that, the server also has a beta version of Plex and Emby — two popular streaming platforms.
- TerraSync: including Server and Client apps, TerraSync is a copy of Synology Drive that allows syncing and baking data of multiple clients.
None has the same level of in-depth customization for functionality as the Synology counterparts. On top of that, some apps are impossible to use.
For example, the VirtualBox app, supposedly a virtual machine manager, doesn't work at all.
The way software works, there's hope that things will get better in future updates and releases.
Unfortunately, the particular case of the T6-423 server is primarily negative. Let's start with its hardware specifications.
TerraMaster T6-423 vs. F2-223: Hardware specifications
Similar to the lesser F2-223, the T6-423 is Multi-Gig ready. It has a better CPU but shares the same RAM configuration. In the end, the extra drive bays are its most significant edge over the older cousin.
Quad-core 2.0 GHz
(Max burst up to 2.9 GHz)
|Intel Celeron N4505
Dual-core 2.0 GHz
(Max burst up to 2.9 GHz)
|Hardware encryption engine
(Upgradeable to 32GB via one slot)
(Upgradeable to 32GB via two slots)
|Compatible drive type
|6 x 3.5" or 2.5"
(drives not included)
|2 x 3.5" or 2.5"
(drives not included)
|2x M.2 slots
|2 x USB 3.2 Gen 2 (10Gbps)
|2 x USB 3.2 Gen 2 (10Gbps)
|8.90 x 5.12 x 5.58 in
(226 x 130 x 218mm)
|8.93 x 4.68 x 5.23 in
(227 x 119 x 133 m)
|8.6 lbs (3.9 kg)
|5.2 lbs (2.4 kg)
|2 x 2.5GbE
|2 x 2.5GbE
|Wake on LAN/WAN
|Scheduled power on/off
|100V to 240V AC
|100V to 240V AC
(per 24 hours)
|≈ 770 Wh
(measured with 6 hard drives)
|≈ 490 Wh
(measured with two hard drives)
|Maximum storage capacity
|120TB (2 x 20TB drives)
|40TB (2 x 20TB drives)
|Maximum local user accounts
|Maximum share folders
|Supported RAID type
Single, JBOD, RAID 0, RAID 1, RAID5, RAID 6, RAID 10, TRAID
|Single, JBOD, RAID 0, RAID 1, TRAID
|Suggested retail price (disk-less)
The odd physical shape, terrible drive bay design
Out of the box, the T6-423 looks rather odd. The server seems to be an internal part instead of a complete product.
By default, it's designed to stay in a vertical position, but you can also place it horizontally — there are even included rubber feet that you can attach to the new "underside" in this case.
But no matter which you use, other than the front, where the drive bays are, the rest of the server seems unfinished. It's like the product managers originally intended to put the whole thing in a case and then change their minds.
And the drive bay themselves are problematic. Each bay comes with a tray to hold a SATA internal drive. Unlike the case of the F2-223 or F2-221, where you can install drives tool-free, you have to use a screwdriver to mount a drive on the T6-423's stray.
The server includes two sets of screws for the desktop (3.5-inch) drives and the other for smaller laptop (2.5-inch) ones. And that's where things go sideways.
For one, the included screwdriver's tip is too large for the screws. You can't use it. It's quite ridiculous. And secondly, with six drive bays, installing the drives — you have to fumble with four little screws for each — can be tedious and time-consuming.
And turning these drives into accessible storage proved to be a big problem in my trial.
Super buggy Storage Manager
As a storage device, there's nothing more important in a NAS server than the Storage Manager, an app that handles internal disks.
And for a 6-bay server with multiple RAID options, the T6-423 has the worst Storage Manager I've used. There are so many things not right about it, little and small.
For example, the only way to make the server work immediately is to put all available drives into a single storage pool during the initial setup process.
But with a server that can handle these many internal drives, you'd want to use multiple storage options, such as a RAID 0 and a RAID 5. And that's exactly what I wanted to try out, and I had the most challenging time with it.
I started with six 20TB IronWolf Pro hard drives with the server. As the server took more than a day to finish syncing two of them into a RAID 1, I opted for 2TB drives for the testing to save time. Still, specific RAID configurations, including TerraMaster's flexible TRAID, required hours to finish syncing.
Initially, building a second storage pool using available drives seemed impossible. The process would start then nothing happened.
At first, I thought the server only worked with a single storage pool. So to experience the server with a different RAID configuration, I had to re-set it up from scratch. It was very frustrating.
Later on, I found out that it was because of the lag. The server's Storage Manager took five to 10 minutes, or even longer, to show a new Storage Pool in the system — the larger the hard drives, the longer the lag.
So, I decided to use a couple of SSDs for the boot volume. Now things are better, but the lag was still there.
And then, when a new storage pool was successfully created, it was also named "Storage Pool 1", so I'd have two or even three "Storage Pool 1" in the system, making it confusing to know which is which.
But after I restarted the server, the system showed them correctly as "Storage Pool 1," "Storage Pool 2", etc.
Long story short, the server's Storage Manager could use some whale-size improvements. The way it works right now, it's impossible for any advanced user to trust it. I didn't. I was scared of its finickiness.
Hopefully, that will happen via OS updates.
TerraMaster T6-423: Extra photos
Besides Storage Manager mentioned above, the T6-423 had other little reliability issues in my trial. Here is a short list:
- Changes not consistently applied: The server often doesn't apply common settings. For example, I set the time zone to Pacific and applied the changes. After the server failed to execute some scheduled tasks, I discovered that it was still using its default Hong Kong time zone. Turned out, I needed a restart for the new zone to be in effect.
- Case-sensitive username: The server uses Linux's default case sensitivity for the username, making it unfriendly to general users who tend not to remember this. Many other NAS servers don't do this.
- Restart often required: Generally, you'd have to restart to ensure that the changes you've made to the server are applied. With the T6-423, what you see on its interface is not what you get most of the time until after a restart.
It's important to note that the issues with the server themselves are not consistent. They might happen, or they might not. But one thing is for sure, something will not happen the intended way.
In other words, during my trial, even the server's bugginess is buggy. That might sound odd, but there's no other way to put it. There's little consistency with the hardware.
Overall, the T6-423 has a big issue with reliability. During my week-long trial, I always felt unsure, worrying that some functions might stop working out of nowhere. And some did, until a restart.
TerraMaster T6-423: Multi-Gig-class performance
With two 2.5GbE ports, the T6-423 did well in my performance tests. I tested it via standard RAIDs, including RAID 0 and RAID 1 (both with two drives), using hard drives and SSDs, and the server delivered fast sustained speeds, though not speedier than the F2-223.
It's worth noting, though, that the server's TRAID performance (not shown on the charts) is significantly slower than RAID 1 (2 drives) or RAID 5 (4 drives). So if you want the best performance, it's a good idea to use a standard RAID.
Unlike the case of the F2-223, the T6-423 ran a bit noisy in my trial. Its fans — even when put in quiet mode — produce enough noise to be a nuisance in a quiet room.
TerraMaster T6-423 6-Bay NAS Server's Rating
Two built-in 2.5Gbps Multi-Gig ports; fast performance
TOS 5 includes domain/LDAP integration, robust interface, TRAID, Snapshot, and more
Six drive bays with multiple RAID options
Extremely buggy Storage Manager; lots of little issues; unmatured OS and apps
Impractical, bulky design, hard-to-reach NVMe/RAM slots
No 10GbE upgrade or IP camera support
The TerraMaster T6-423 is a missed opportunity. The server could be a much better network storage hardware if it improved based on the F2-223. Instead, the completely new design makes it impractical and annoying to use.
And the currently buggy operating system, lackluster apps, and other little oddities don't help. The server fails to live up to its intended goal of being an advanced server, making it a bad deal even for the relatively low $700 price tag.
Use it as a bare-basic NAS device with fast throughout, or opt for the much more refined Synology DS1621+ instead. The latter will save you from a ton of headaches down the line.