The benefits of flash storage are clear - speedy operation, shockproof, silent and tiny in size. We take a look at eight of the best options for the Mac.

Almost all Macs now run on flash storage as standard. The benefits are clear – incredibly speedy operation, shockproof, silent, and tiny in size. There’s been a trade off though, as our internal storage allowances have shrunk, unless we configure an upgrade at time of purchase at the Apple Store, with a hefty premium.

But the same technology that makes the Mac feel so fast is also easy to find in the form of portable external storage. USB thumbdrives, once slow and small, have expanded greatly in capacity and performance, and now challenge more traditional drives based on notebook SATA drives in a caddy. Meanwhile many of these pocket-sized drives have shrunk in size, some of them taking advantage of the increasingly popular mSATA flash modules which are only a small fraction the size of a 2.5in SATA disk.

To take advantage of the very high speed and low latency of flash memory, a fast drive needs a fast interface. Mac users are spoiled for choice. Replacing USB 2.0 and FireWire 800 as data interfaces, we now have USB 3.0 and Thunderbolt. Neither is perfect, each with their own pros and cons.

Thunderbolt

Thunderbolt is technically the better protocol but it has high power overheads and is more difficult to implement, making Thunderbolt drives less common and more expensive.

Thunderbolt’s data pipe should be wide open to let solid-state drives channel data as fast as they can run, but if you want your portable drive to be truly portable and mains adaptor-free, there are problems. Power demands of the Thunderbolt electronics and even the cable itself brings compromises to performance so that bus-powered flash drives currently operate well below their potential.

USB 3.0

It’s now about impossible to find any form of USB storage drive that is still using USB 2.0 – even many small thumbdrives are compatible with the so-called SuperSpeed standard. But that doesn’t mean every USB 3.0 flash drive will deliver scorching speed. Small, inexpensive thumbdrives typically use lower-grade and slower flash, making them more disposable in our flash-rich world. Look out for higher quality and inevitably more costly drives which are more likely to take advantage of top-grade NAND silicon.

For truly speedy operation the flash memory and controller must be up to spec, but the the correct drivers must also be loaded. By default USB 3.0 storage uses a relatively slow transfer protocol called Bulk Only Transport (BOT) which will severely slow down fast flash.

A revision to the USB 3.0 protocol that’s receiving more widespread support now is USB Attached SCSI (UASP) mode. UASP importantly also enables multi-threaded operation to really accelerate connected USB 3.0 drives to the level of an internal drive.

Full-speed UASP operation first requires support from the storage device, and then for a kernel extension (kext) to be loaded when it’s mounted by OS X. Thankfully this happens automatically with supported hardware; if you use Windows as well and want to get the best out of a UASP device there you’ll need to find and install a driver.

While flash can be packed into the tiniest of pendrives, the best performing devices are still those that include a separate managed solid-state drive inside, such as SATA- and mSATA-based pocket drives. Their SSDs include controllers that maintain consistent operation even after heavy use, as well as improved wear levelling routines to increase longevity.

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Conclusion

There’s less reason to worry about running out of storage space on limited-capacity flash-based Macs, now that similarly quick external storage can now be plugged in at will. Thanks to the two options of USB 3.0 and Thunderbolt found on all modern Apple computers, it’s easy to offload files big and small to a detachable flash drive.

If portablility or pocketability are your aim, the humble thumbdrive can now be found with speed that’s starting to rival internal drives. And capacity has sky-rocketed too, as we found from two of the most transportable devices available – the block of metal that is the Kingston Predator and the ethereally light Integral Portable SSD. Both these will become available in up to 1 TB capacities, the former at around £1 per gigabyte, the latter at half that price. Neither were the quickest in our tests, but will seem lightning-quick compared to USB 2.0 devices of a couple of years ago.

Lexar and SanDisk offer the smallest classic-style thumbdrives with fast flash and USB 3.0 connections, good for most everyday jobs, and both are available in sizes from 16 to 64 GB. The SanDisk offers the best value; the Lexar a touch more class in its build quality.

For top performance today, and for the best bet in long-term longevity too, look for an external flash drive based on a regular SATA SSD. This should have the best-quality flash memory inside that is likely to last for years before starting to flake out, and dedicated on-board controllers should maintain performance and reliability over that time.

Both LaCie’s external flash drives go this route, using Micron and SanDisk solid-state SATA drives that are well matched to the speedy interfaces available. The Porsche Design unit will suit executive desktop use, with a style to complement Apple’s MacBooks, while the Rugged is a more no-nonsense design to suit more carefree owners. The Rugged is also one of only two flash drives to give a Thunderbolt option. Compromises have to be accepted in bus-powered Thunderbolt drives until chipsets become efficient enough to run at full speed, although owners of pre-USB 3.0 Macs made between 2011 and 2012 will find that Thunderbolt is the only way to get close to the performance fast flash can provide.

Elgato is similarly afflicted in the Thunderbolt department, which is a shame as its internal SSD is still one of the fastest SATA drives in the business, held back by the bridge electronics that have been derated to keep within strict power consumption boundaries. Nevertheless its newfound USB 3.0 port gives a better taste of the true speed available for this smart and solid storage device.

Combining minute size with performance that flattens nearly all competitors is the Axtremex Micro SSD. Not only does it have the finest balance of sequential read and write speed, it also proved incredibly quick at the small file level, which recommends it as a general-purpose data drive – even a full-specification boot drive – and not just a speed king for bulky media files.

At £300 for a 256 GB drive, its £1.17 per gigabyte cost puts it in the top price bracket, although it’s still effectively cheaper than the Elgato, LaCie Rugged and Lexar products.

Detachable external storage is a great way to make fast backups and exchange large files with others, but more fiddly if you just want somewhere to keep files you’d rather have on board. If you’re thinking of using external storage to combat the price of Apple’s upgrades, you might like to think again – it now seems it’s not necessarily the cheapest way to get around the Apple storage tax: at £240 for an added 256 GB of flash storage on a new MacBook Air – which works out as 94p/gigabyte – Apple’s upgrade prices now don’t look as bad as the first glance may suggest.