The F5-422 achieved high network transfer speeds with open file transfers in our multi-client tests because of its bundled 10 GbE port. I didn't bother much with the two 1 GbE ports, which need a compatible switch to be teamed, and they still wouldn't be as fast as the single 10 GbE port. The major advantage of having multiple Ethernet ports is that traffic is dynamically reassigned to another physical link if one fails, so there is no downtime. This is big for servers that need to be available 24/7 without any issues. That having been said, if you require the highest possible transfer speeds, make sure to use the 10 GbE port with a compatible switch, which is also much more affordable a combination than just a few years ago.

There is a major drop with encrypted files, which is strange because the CPU supports Intel's AES New Instructions. The issue is most likely in the software, so an OS upgrade should fix it. I also noticed low IOPS performance in the multiple-client tests, so this is an area that requires attention as well, especially if you plan on using this NAS with applications that move large numbers of small data packets.

TerraMaster vastly improved its operating system, but it still has lots of ground to cover before catching up to QNAP's and Synology's operating systems. This is not an easy task as the aforementioned brands have considerably more years in the market. With the proper feedback and help of good programmers, everything is possible, though, even in a short period of time. TerraMaster's Operating System (TOS) requires a number of improvements and touch-ups here and there, and the bundled HDMI port should be utilized as soon as possible. If TerraMaster wants to exploit the capable hardware fully, it also needs to focus more on secondary apps that enhance the server's capabilities. For example, there is no surveillance app or VM and multimedia software packages but for Plex Media Server. If you need such applications, you had better go with a Synology or QNAP NAS, although either would cost more if you want hardware specifications similar to the F5-422.

Lately, more and more NAS vendors provide btrfs support because of the enhanced security options this file system offers, including full system snapshots, checksums, and rollback. The significant advantage EXT4 still provides is slightly increased performance, but I apparently will have to change my default test filesystem to btrfs to keep up with the trend.

The outcome of today's review is that the F5-422 performs well with multiple clients in scenarios that don't involve encrypted files or high IOPS performance. Although its hardware is highly capable, there is still a hold-up in IOPS performance, which could probably be fixed with a software update. Pricing looks high, but compared to competing offerings that feature a 10 GbE Ethernet port, it is fair. A price closer to $500 would make it much more attractive, though. It would also be nice to see M.2 support in a future version of this model to allow for SSD caching without sacrificing a drive slot.