OWC Mercury Elite Pro Dual

Price when reviewed

Resembling its ThunderBay 4 stablemate after a crash diet, the OWC Mercury Elite Pro Dual is a two-bay desktop RAID unit with both Thunderbolt and USB 3 interfaces. Our review sample was supplied with two 2GB, 7,200rpm Toshiba hard disks – a configuration OWC sells in the US through its parent company MacSales; in the UK, it’s sold chassis-only. Still, bought separately, the drives will set you back only £120 for the pair, and you can choose your own drives based on your budget and requirements.

OWC Mercury Elite Pro Dual

Inserting the drives is a palaver, requiring you to remove the inner chassis from the outer enclosure, then insert both units at a slightly awkward angle. Like the ThunderBay 4, this is an extremely solid, well-constructed drive. Unfortunately, again like its larger sibling, it’s noisy, emitting a noticeable hum from the fan when the drives are in operation.

OWC Mercury Elite Pro Dual review

Unusually, the Elite Pro Dual uses a hardware RAID controller, which provides a choice between RAID0, RAID1, a single-volume Span mode and two independent drives, via the adjustment of a screwdriver dial at the rear. It’s possible to change the RAID configuration at any time, although OWC warns that this will destroy all data on the disks. Perhaps as a result of this, changes must be confirmed by pressing the small Confirm button with a paperclip.

The benefit of this approach is that there’s no faffing with the Elite Pro Dual. It presents itself both to OS X and Windows 8.1 as a single volume, preformatted to HFS+ but easily reformatted to NTFS without the need for proprietary utilities. Where other RAID devices caused problems while running under Boot Camp on the Mac Pro, the Elite Pro Dual behaved impeccably. On the software front, OWC provides a selection of disk utilities, backup utilities and shareware.

With the two Toshiba drives in RAID0 configuration, the Elite Pro Dual performs well over Thunderbolt, reaching write speeds of more than 300MB/sec and read speeds in excess of 350MB/sec in OS X, with similar results in Windows. That performance doesn’t degrade when connected over USB 3, either.

OWC Mercury Elite Pro Dual review - front and rear views

Overall, the Elite Pro Dual is a great halfway house between single-drive desktop enclosures and larger, high-performance RAID devices. It provides plenty of space and bandwidth, plus impressive transfer speeds, but in a slightly smaller, less obtrusive box.

And, while fitting the drives yourself may be off-putting, it makes the whole package comparatively inexpensive, with the drives and enclosure costing a shade over £300. At this price, it isn’t merely a cheaper option than the larger RAID units, but also a viable alternative to the non-RAID desktop hard drives.

OWC ThunderBay 4 specifications

Maximum capacity4TB
RAID support0, 1m, Span, Indepedent drives
Interface2 x Thunderbolt, 1 x USB 3
Power supplyExternal (12V DC)
Spindle speedN/A
Size71 x 229 x 133mm (WDH)
Buying information
Warranty3yr RTB

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