We know that adding drives to a RAID array can help improve performance. But does adding storage to a NAS device really help push throughput higher? We put four-bay and five-bay units from Qnap up against each other and benchmark their transfer rates.

Qnap is a network storage device manufacturer with a wide range of products. The company portfolio contains everything from media players to network storage solutions for security cameras. Its NAS device product line is probably the area where the company has its strongest brand recognition, and the manufacturer aims at offering lots of options.

As a result, many of its NAS devices come in several different varieties. The TS-x59 Pro series is available with two, four, five, six, and eight drive bays, for example. They all share the same base platform: 1 GB DDR2 memory combined with a dual-core Intel Atom D510 CPU.

Using a single platform is justifiable from a business point of view. Offering several varieties of the same basic configuration means serving different customer segments, while keeping development costs low. Taking the TS-x59 Pro series as an example, the two-drive bay TS-259 Pro version (around $599 USD without storage) is targeted toward sophisticated users who require a NAS device for home network use. The eight-drive bay TS-859 Pro is aimed at the enterprise segment, which is reflected in the price ($1580 USD without hard drives). The four- to six-drive bay units cost between $909 and $1249 USD, and might attract both business and enthusiast users.

* Approximated prices without hard drives; these may vary

Comparing the TS-459 Pro and the TS-559 Pro with four and five bays, the question we want to answer is: are there any differences between the two devices, other than the fifth drive bay? Is it worthwhile for ambitious users to pay extra for the five-bay unit, or are you better off with the four-bay version, in terms of value for money, as well as speed? And finally, what are the advantages of a fifth drive in the NAS device?