A Quick Look at TOS 5.1

Even thought it's been over four years since we last looked at a NAS from TerraMaster, we won't be doing a deep-dive into TOS 5.1. This is because TerraMaster is about to release TOS 6, so we'll wait until that is out to do take a proper look at the operating system. However, we'll still go over some of the features of TOS 5.1—above you can see the typical desktop view that has become something of the norm for pre-built NAS appliances.


Once the setup has finished, you're greeted by the following, first you get to see the storage pool to make sure everything was set up as expected and this is followed by the security advisor that goes a bit bonkers, warning that multiple features aren't enabled. These are not critical issues and TerraMaster might want to re-think their way of informing the user about things that they should consider doing to keep the data on their NAS safe, instead of throwing out red exclamation marks in warning triangles.


That said, TOS 5.1 is a fairly modern NAS OS, despite already having been around for a few years already. TerraMaster might not be able to compete with QNAP and Synology when it comes to the amount of native apps that are supported, but TOS 5.1 has no less than 62 native apps that are maintained by TerraMaster, plus another 135 community maintained apps. We'd like to see some better integration of the community apps though, as to install them, you're taken to a third party website where you have to download them to your computer, before you upload them and install them on the NAS. This is awkward, and it's something TerraMaster's competitors have solved much more elegantly. TerraMaster also supports Docker, in case the available apps don't meet your requirements.

As TOS 5.1 is a more mature OS than Ugreen's UGOS, support for features like iSCSI and a native VPN server are part of the package. However, as we pointed out earlier, the HDMI port on TerraMaster's line of NAS appliances doesn't support direct media playback, but a media server with DLNA/UPnP support and 4K video transcoding is present, as well as native support for Emby and Plex, making the F4-424 a fully featured media server in a few simple clicks.


The control panel is pretty straightforward, but also a bit lacking in terms of features compared to QNAP and Synology. However, this may be a good thing if you're looking for a NAS that's less complex to use. TOS 5.1 supports three types of SSD caching, external USB storage enclosures, virtual disks and hot spares for those that want more advanced storage features. All typical file servers such as Samba, FTP, NFS and Apple's AFP are supported, as well as Rsync and WebDAV. Network bonding is also supported and we gave the adaptive load balancing a try, but we didn't see any performance benefits from using this, despite the OS claiming that this is meant to work without a manage switch. For owners of a managed switch IEEE 802.3ad dynamic link aggregation, as well as balanced xor and something TerraMaster called active-back, also known as failover, are supported.

What is a bit lacking is the resource monitor, as it doesn't show temperatures or fan speeds, although everything else that you'd expect such as average system load and memory usage are present. TOS 5.1 supports a wide range of language translations and handles non-Unicode languages. One advantage TOS 5.1 has over Ugreen's UGOS is that you can easily enable or disable media indexing with a single click, which can be handy in situations like the one we experienced when testing the NASync DXP4800 Plus where the media indexing interfered with our testing.

Overall, TOS 5.1 is a pretty competent OS, but we also ran into a couple of weird bugs that shouldn't be present at this point. Both are related to the shared folders and in the first instance, we were unable to add a shared folder, as the option was greyed out and this required a software reset of the NAS to be resolved. The second issue was that shared folders wouldn't show up over Samba, even though they were present in the file manager on the NAS. We were unable to resolve this issue during our testing. These issues might simply be due to our testing where we swapped between multiple RAID modes and volumes, but these types of bugs should simply not be present as they're preventing the NAS to work as intended.