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QNAP TS-251B-2G 2-bay NAS Review

The TS-251B is QNAP's first 2-bay NAS to have an integrated x2 PCIe slot, and indeed it's the first of any 2-bay models we've seen that supports one. Although with just two drives bays there isn't much in the way of data security (just RAID 1), the addition of the PCIe slot allows the TS-251B to support QNAP's QM2-2S and QM2-2S-220A SATA SSD expansion cards and the QM2-2S1-G1T SATA SSD & 10GbE hybrid card, plain dual and single port 10GbE cards and USB3.1 cards.

QNAP quotes Sequential Read/Write performance figures for the TS-251B at 112MB/s for both with a 1GbE interface, speeds we could confirm with the ATTO benchmark. The tested unit produced a read score of 119MB/s for both RAID 0 and RAID 1 arrays, with writes at 117MB/s for RAID 0 and 118MB/s for RAID 1.

The Intel AES-NI hardware-accelerated encryption engine in the TS-251B works well but it's more effective when dealing with encrypted writes than reads. It drops 17MB/s in RAID 0 and 13MB/s in RAID 1 when writing encrypted data, against a 22MB/s drop for both arrays when reading encrypted data.

Any NAS worth its salt should be easy to set up and easy to use for both newcomers and experienced users alike. QNAP’s QTS is quick and easy to install using its easy to follow wizard-based setup procedure. Once installed the QTS operating system is clean and easy to navigate through for beginners thanks to its graphical interface, but for more experienced users it’s packed full of features hiding behind the bling in a comprehensive control panel. QNAP updates the OS regularly, adding to and updating its features and packages in the Apps Centre.

For instance, a recent addition to QTS is Notification Center. This is a very useful app that consolidates system logs and notifications for all the apps on the NAS into one single app. It supports flexible rule settings for easier NAS management and allows for more notification methods including email, SMS, instant message, and push notification either singularly or as multiple methods. It also allows for the definition of specific rules for notifications to be sent via specific methods.

All in all, then, the TS-251B is a solid 2-bay NAS. By nature of being a 2-bay NAS it can't offer much in the way of data protection, but the x2 PCIe slot is useful and we like QNAP's QTS software.

We found QNAP's TS-251B-2G on sale for £301.20 (inc VAT) on Span.com HERE.


  • PCIe slot.
  • QTS software.
  • Overall performance.


  • Limited data protection.

KitGuru says: Although it's aimed at home/SOHO users, with its PCIe slot and support for 14TB drives, QNAP's TS-251B becomes a much more useful 2-bay NAS for small businesses when compared to standard dual-bay units.

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Rating: 8.0.

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