OWC Mercury On-The-Go Pro full review

Practically every portable hard drive now comes with a USB 3.0 port, but for Mac users in particular there’s still a call for FireWire connectivity.

FireWire 800 was until relatively recently the fastest bus available for desktop drives and there are many pre-USB 3.0 Macs in use which can benefit from the two-times speed over USB 2.0. Which is why the OWC Mercury On-The-Go Pro is such a good idea – it’s a particularly fast pocket solid-state drive with both USB 3.0 and FireWire 800 ports.

OWC Mercury On-The-Go Pro review: Storage capacity

It’s impossible to miss what powers this portable drive – the totally transparent polycarbonate shell reveals OWC’s own branded SSD inside. The drive is available in three solid-state capacities of 60, 120, 240 or 480 GB.

Additionally, if higher capacity and lower budget are more important than speed and resilience, there are alternative hard-disk versions: 320, 500, 1000 and 1500 GB with standard 5400 rpm disks; and 500 or 1000 GB with slightly faster 7200 rpm disks.

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Or if you’d like to roll your own, you can buy an empty enclosure and insert the 2.5in drive of your choice.

Our sample with 240 GB SSD is priced at $200 from the maker’s US website, although this will be subject to shipping charges, import duty and VAT. We’ve also seen it for sale in the UK through Mac Upgrade Ltd for £234.95 inc VAT and delivery.

The SSD in our sample was a 240 GB OWC Mercury Electra 6G, an electric blue-coloured device with SATA Revision 3.0 interface. This flash drive is based on a SandForce SF2281 controller, a popular choice with brands like Corsair, Intel and OCZ a few years ago if now rather less fashionable since its reliance on data-compression algorithms means speed drops when writing MPEG and JPEG files.

That will likely be less of an issue here though since the middlingly fast USB 3.0 interface already does a good job of slowing down the transfer of data when compared to  internally mounted drives.

OWC Mercury On-The-Go Pro review: Build and Design

Viewed from the top, the 140 x 88 mm case clearly shows all the workings inside. There’s OWC’s SSD attached to a small PCB, and this handles conversion between the drive’s native SATA, and USB 3.0 and FireWire protocols. For the latter FireWire connection a custom Oxford 944 chipset is used, while ASMedia takes care of USB.

Two FireWire 800 ports are offered on one end, allowing the drive to sit within a chain of other FireWire devices. To their left is a single Micro-USB 3.0 port, and on the far right is a DC power input – although we see little need for this these days now that most USB ports deliver enough current. A small slide switch here means you can power the drive down without disconnecting. Just remember to unmount the volume from the Mac first or else you’ll get an annoying alert.

When the drive is connected and switched on, a small LED floods the front of the clear case with its cool blue light.

To help prevent the SSD from getting too warm in extended use, it’s attached to an aluminium heatsink with extruded fins. This just protrudes from the underside of the casework, and is held just above the desk by four flat rubber feet.

Included in the box is an invaluable black PVC carry pouch with room for the provided short cables too, one each for FireWire 800 and USB 3.0.

OWC Mercury On-The-Go Pro review: Software

As a Mac specialist, OWC also provides a potentially useful directory of software on the drive. This includes free open-source software of interest to the Mac user as well as productivity tools, utilities and audio/video tools. There’s even a free copy of Intuit QuickBench, which we routinely use to test storage performance in OS X.

OWC Mercury On-The-Go Pro review: Performance

Using a MacBook Pro (15-inch, Mid 2012) we tried the USB 3.0 interface first, and measured speeds up to 430 MB/s. In our experience that’s approaching the top speed currently available for USB 3.0 storage devices, when used in UASP mode. The quickest we’ve seen was with the Axtremex Micro SSD, which reached around 440 MB/s.

Averaged over data sized from 2 to 10 MB, sequential speeds from the OWC drive were 422 MB/s when reading data, and 381 MB/s for writing. With 20 to 100 MB data, results averaged 429 and 384 MB/s respectively.

Looking at small file transfers, 4 to 1024 kB, the OWC Mercury averaged 215 MB/s sequential reads and 202 MB/s for writes. Random reads were only a little lower at 188 MB/s while random writes remained at 202 MB/s.

In a real-world test of writing large media files, we copied around 15 GB of MPEG-4 video from MacBook Pro to OWC drive through USB 3.0. This took just over 90 seconds, suggesting a write speed with incompressible data of only around 160 MB/s.

Turning to FireWire 800, we saw perhaps the fastest performance we’ve measured from this type of connection. Sequential reads for all data above 20 MB stayed steady at 85 MB/s, and writes at 83 MB/s. Small files transfers averaged 56 and 58 MB/s for random reads and writes respectively.

These lab results suggest that even for FireWire connections, the OWC Mercury will be very responsive and be able to juggle reading and writing data very well.

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