One of the reasons I like Macs is that their useful life tends to be significantly longer than that of a typical Windows machine. This is especially true of the pre-Retina MacBook Pro models, where it’s trivial to upgrade both the RAM and the drive.

I’d previously swapped out the 750GB hard drive and optical drive that came with my late-2011 MacBook Pro 17 for two 1TB hard drives. Along with a RAM upgrade, that gave me a 16GB RAM, 2TB hard drive machine. The plan was to use the machine in that form for a year or two, then do a further upgrade to SSDs once 1TB models arrived and fell to a halfway sensible price.

When that finally happened, and I did the upgrade, that gave me two 1TB hard drives surplus to requirements. I could have placed each into its own external drive caddy, but one 2TB drive is more useful than two 1TB ones, so I decided instead to try out OWC’s Mercury Elite Pro mini. This is an external enclosure for two 2.5-inch drives, which supports both USB 3 and Firewire 800, drawing power from either source – making it a portable drive without the need for external power … 

Installing drives into the enclosure is trivial even for non-technical types, thanks to the extremely comprehensive instruction booklet with clear, step-by-step photos. If you can use a screwdriver, your skill-set is complete.

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Undoing two Philips screws on the backplate allows you to slide out the innards.

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Inside, OWC supplies the eight Philips screws you need to secure the two drives in the caddy. Remove these, and the silica gel packet, and you can then slot in the two drives. Simply place each one loose in the caddy, line up the SATA connection with the slots and push firmly into place.

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You do have to press down a little more firmly on the right-hand drive, which sits on top of a clip holding two cables, but it’s a simple, 10-second job.

Once the drives are in place, flip the unit upside-down and insert the four screws which attach each drive.

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The instructions suggest you hold the unit in your hand to press the drives flat against the bottom-plate while doing this, which is easy to do.

Once secured, you need to set three DIP switches to tell the unit which mode you want. There’s a choice of RAID 0, RAID 1 and Span. I chose RAID 0. This makes both drives look to OS X like a single drive, with data spread across the two. It does, though, mean that a failure of either drive will result in loss of data. This isn’t a great concern to me, as it will be used as a media drive, so everything on it could be re-downloaded if needed.

If you want internal backup, RAID 1 gives you the full capacity of one of the drives, and mirrors all the data to the second one. Finally, if you are using two drives with different capacities, Span mode acts like RAID 0 in that it makes it appear to OS X as a single drive, writing data to one until that drive is full and then writing further data to the second one.

That done, slide the caddy back into the enclosure and re-attach the back-plate using the two screws you removed earlier.

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That’s it: no cables to attach, only a total of ten screws. Connect to USB (newer Macs with USB 3 ports) or Firewire (older Macs), slide the power switch on and you’re up-and-running. Both cables are supplied, and both power the drive from the port.

With the job complete, you have a stylish-looking drive that matches the quality of any ready-made drive out there and is an excellent match for a Mac.

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There are two Firewire 800 ports, so you can daisy-chain them if desired, though you will need external power to do that. OWC offers an optional power supply for this use.

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In use, two blue LEDs light up to confirm both drives are operating.

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With RAID 0, I was seeing both read and write speeds in the 60-70MB/s range on Firewire, which is on a par with what I’d expect from a single external drive.

At $89.99, it’s not the cheapest solution out there, but I do think it’s a decent value for what you get. It’s a very stylish design, very solid build – and the built-in RAID gives you the convenience of combining the capacity of two drives into one. It’s available direct from OWC, with free shipping.