With a potential capacity of 7.5 terabytes, comprehensive connectivity and enough sharing and networking functionality to suit almost any need, QNAP’s latest network storage offering is an excellent choice.

Billed as a high-end storage device for small businesses and corporate environments, the TS-509 Pro network-attached storage (NAS) device looks more functional and rugged than its smaller brother, the TS-409 Pro. Rather than a single perforated grille, the device’s five drive bays are visible. Each of them is lockable for extra security. The integrated display is useful for displaying basic configuration and operating information.

The device offers two separate Gigabit Ethernet ports for dual shared networking, as well as an eSATA porta for expanded storage and five USB ports for backup and USB-based UPS devices.

Possibly the biggest improvement compared to the TS-409 Pro is the ability to hot swap hard drives. We often found problems attempting to hot swap drives while the TS-409 Pro was on, but the TS-509 Pro easily recognised and adjusted once a new hard drive was inserted, using a beep to alert users when the drive is ready to use.

The majority of the device’s administrative features are accessible through its Web-based interface. It isn’t as attractive or straightforward as the Synology Disk Station DS408's, but it is certainly functional. Users can administer drive and RAID settings, with the ability to remotely expand RAID volumes under RAID 0/1/5/6 and JBOD configurations. After overcoming the slight learning curve, even novice users can easily administer user groups and other settings. There are also plenty of advanced features for the technologically adept to work with.

The integrated Download Station can download files using the HTTP, FTP and BitTorrent protocols, and unlike the TS-409 Pro you can also schedule downloads. The UPnP, Multimedia and iTunes servers are commendable inclusions.

The performance of the TS-509 Pro is particularly impressive. We transferred 28GB worth of data between a desktop PC with a Western Digital VelociRaptor (WD3000GLFS) and the TS-509 Pro with two Western Digital RE2 GreenPower (WD1000FYPS)s installed through a Gigabit switch, with surprising speeds. The unit managed a write speed of 31.6 megabytes per second. Read speeds were even faster at 33MBps, while the speed averaged 15.4MBps when copying files from one location on the NAS device to another.