The four-bay, Western Digital Sentinel DX4000 4TB is the only NAS box we've tested recently that uses Microsoft's Storage Server 2008 R2 Essentials for its operating system. All other comers are Linux-based, which turns out to be a big advantage. Despite being a well-conceived piece of hardware, the Sentinel DX4000 doesn't deliver enough performance or features to compete head-to-head with the speed demons we've seen from QNAP andSynology. See also: Group test: what's the best NAS device?
Not a company that's content to step back in time, Western Digital has equipped the DX4000 with state-of-the-art, trayless, quick-change bays (simply slide in the drives), dual gigabit ethernet ports, and two USB 3.0 ports. Pairing ethernet ports provides failover protection in case one connection goes down, but the NAS box doesn't support aggregation for increased performance. USB 3.0 means faster local backup of the box, but the absence of eSATA might kill the deal for prospective buyers who want to use existing eSATA drives to back up the DX4000. The WD's NAS box even has dual AC jacks, though it ships with just one power brick. Visit Netgear ReadyNAS NV+ v2 review
Microsoft's Storage Server 2008 R2 Essentials is much easier to install than Windows Home Server, an OS that some cheaper NAS boxes have employed in recent years. Whereas WHS required an installation disc, Storage Server 2008 has all of its software loaded on board the box. Surf to the Sentinel DX4000's IP address, follow the prompts, and you're golden. Once through initiation process, you use the supplied Connector software to access and configure the box. Advanced software features include DLNA-certified and iTunes media streaming, but not much else, though Western Digital does expect to add online backup soon.
Storage Server 2008 R2 Essentials automatically configures drives to an appropriate RAID level, and reconfigures them as you add drives. With two drives on board, as on our test unit, the default mode is RAID 1 mirroring; add a third drive and the unit will switch to RAID 5.
With the same dual-core Intel Atom D525 CPU that the very quick QNAP TS-459 Pro II uses, but twice the memory (2GB), the Sentinel DX4000 ought to have delivered better performance numbers than we saw. In our tests, the box wrote our 10GB mix of files and folders at 36 megabytes per second, wrote our 10GB single file at 58 MBps, and read the large file at 83 MBps--all middle-of-the pack numbers. On the other hand, it was the fastest of the multibay NAS boxes we tested at reading the mix of folders and files, performing the task at 57 MBps.
Though not the most feature-rich of NAS boxes, the Sentinel DX4000 provides all of the basics and is certainly the easiest model for non-IT types to install and configure. It's not cheap, but it is a solid, well-supported product that is generally worthy of inclusion in any small business's NAS purchasing conversation.