Axtremex Micro SSD review - Portable flash drive
USB 3.0 promises super-speed data transfers, but external storage – even flash drives – never comes close. The Axtremex Micro SSD was designed to make amends by delivering high speed in a tiny device.
In the world of USB gadgets, and in particular storage devices, it’s commonplace for manufacturers to claim performance of their products exactly equal to the nominal USB specification itself. Take such claims with heart-threatening pinches of salt.
In the days of USB 2.0, for instance, we’d see drives boasting ‘up to 480 Mb/s’. In reality, USB 2.0’s top speed was actually half that, and allowed transfer speeds only around 240 Mb/s. That works out at 30 MB/s, since storage performance is typically measured by the passage of bytes rather than bits over time.
Now with USB 3.0 we’re seeing equally fictitious marketing claims of ‘5 Gb/s’ everywhere. Which would translate to 625 MB/s of course. Yet most external USB 3.0 drives, even those using the latest flash silicon, rarely get over 200 MB/s.
There are several reasons why the consumer is being shortchanged on read versus advertised speed. Yet new hope for decent USB 3.0 performance that better approaches that of internal SATA storage is now being heralded by the Micro SSD from UK company Axtremex.
Why USB 3.0 is slow
There are several reasons why USB 3.0 is underachieving. Firstly, there’s the difference between the so-called PHY layer, and the real-world transfer speed. So while a computer may be processing bits on the physical layer at the rated speed, the rate of real data channeled by the user may be considerable lower.
The classic example is in wireless data comms like 802.11, where actual throughput is lucky to reach one-third of the PHY sync speed, due in the main part to forward error-correction overheads.
The second reason for slower-than-spec USB storage is underperforming drive electronics. To save money and reduce overheating, low-power chips may be fitted, throttling potential performance in the process.
But besides those factors, USB is also flawed as a performance data transfer standard. It’s built to be simple and inexpensive to implement, using a Bulk Only Transport (BOT) transfer protocol that has but one thread and relies on simplex operation – one-way traffic at a time.
One solution is to roll out the venerable SCSI standard, squeezing it within the USB pipe, unlocking full duplex operation and able to theoretically exceed the 400 MB/s or higher speeds available with recent NAND flash storage.
Which brings us to the Axtremex Micro SSD, a baby flash device that can take advantage of SCSI over USB: also known as UASP or USB Attached SCSI Protocol.
Axtremax is an Ilford-based company specialising in solid-state storage products. The company’s Micro SSD is a tiny flash drive sporting up to 256GB of storage space, all enclosed in a very palmable and tactile slim pebble of zinc alloy.
Outwardly it’s a simple object, 58g of satin-finish metal with a chamfered top, rounded corners, and a single Micro-USB 3.0 port on one end.
Our sample was pre-production, unmarked with any proprietary logos although we understand that the final version will carry Axtremex branding.
Inside, the drive is built around a Toshiba mSATA SSD, and available in capacities of 32, 64, 128 and 256 GB. The enclosure is barely larger than the small mSATA circuit board itself.
Pricing is not fully confirmed yet before the unit goes on sale, but we understand the smallest 32 GB will be around £130, with the following capacities at around £150, £180; and the largest 256 GB model we tested may be about £300.
That Toshiba SSD inside is effectively the mini version of the Toshiba THNSNH512GCST that we tested previously in full-size form, a high-performance 2.5in SATA 6Gb/s SSD with excellent sequential and IOPS ratings.
In charge of SATA-to-USB conversion is an ASMedia ASM1053 chip. It’s with the help of this second-generation single-chip USB 3.0 solution that the Axtremex Micro SSD can use the important UASP technology to allow USB 3.0 to perform more successfully.
The USB Attached SCSI Protocol allows PCs to talk to flash storage over a high-speed serial protocol, based on the venerable but versatile SCSI system first devised in the 1980s.
Without a dedicated channel like UASP, even the best flash silicon is held back by ‘5 Gb/s’ USB 3.0. In our initial tests of the Micro SSD using standard USB drivers we saw transfer speeds of around 215 MB/s reads, and 235 MB/s writes in Windows. In OS X, best read/write speed was better but still underwhelming at around 250 MB/s.
Axtremex Micro SSD in Windows: Performance
Getting UASP to engage may be far from straightforward in Windows, we found, where many factors can prevent full operation.
Matters were initially complicated by a choice between two distinct Micro SSD models available from Axtremex. We were expecting a UASP-compliant drive; but the initial sample featured Windows To Go (WTG) functionality, which allows business users to install a bootable enterprise version of Windows 8 onto the drive.
We’ve tried WTG before, and found it to be a very useful feature, letting us boot into Windows 8 without actually installing it on a PC, and thereby reminding us just how entirely unfit for business is Microsoft’s schizophrenic OS.
Having booted into Windows 8 from the WTG version of the Micro SSD on our test-lab laptop and established it could work as well as could be expected, we deleted Windows 8 and reformatted the drive ready for benchtesting.
Only after disappointing test results from this first sample did it come to light that WTG and UASP are mutually incompatible. A dedicated UASP version of the Micro SSD was required.
In Windows, you will also need an Intel Z77 chipset or better on the PC motherboard. Then you will need to install a new driver from the motherboard vendor. In our case, the IDG UK testbench PC uses an Asus P8Z77-V PRO motherboard, and we loaded Asus’ ‘USB 3.0 Boost’ driver and software utility.
Then you will need to ensure you connect the device to the correct type of USB 3.0 port. On this Asus motherboard, the right-hand set of two are run by an Intel chipset. The left-hand pair run through an ASMedia chipset. To get UASP operation, we had to use the ASMedia-controlled ports since UASP is not support by Intel’s USB 3.0 ports.
At least not in Windows 7. After more research Axtremex uncovered the important information we needed:
‘To enable UASP support for Intel's USB 3.0, it is required to use Windows 8. The native Intel USB 3.0 UASP solution is only supported under Windows 8.
‘The whole process changes when using new Asus motherboards such as Intel's Z87 based motherboards. The new motherboards feature onboard UASP USB 3.0 controller and will automatically provide performance boost when a UASP device is plugged in.’
Using the P8Z77-V PRO motherboard’s ASMedia USB 3.0 ports and having UASP switched ‘on’ in the confusing Asus software did give better multi-threaded performance in our tests, but lower peak sequential speeds.
It’s worth noting that even without UASP the Asus software also allows something it calls Turbo mode, which will accelerate sequential speeds. In our tests in Windows 7 with the Intel ports and using Asus’ Turbo software, we saw up to 422 MB/s sequential reads and 400 MB/s writes.
With the second sample in place and UASP now engaged, and using the same CrystalDiskMark 3.0 benchmark test in Windows 7, and discovering which set of USB 3.0 ports to use, sequential reads and writes now hit 303 and 341 MB/s respectively.
That’s well below the non-UASP Turbo mode results. But importantly, decent random read/write performance with queued data showed the drive was now operating correctly.
Single-thread random read/write performance was modest by the standards of the best SATA 6 Gb/s drives installed internally, but still quite fast at 16 and 21 MB/s, for 4kB reads and writes respectively.
At QD=32 for random 4kB data, the UASP-enabled Micro SSD rose to 146 and 114 MB/s; that suggests a respectable peak read IOPS of around 37,000.
Axtremex Micro SSD in OS X: Performance
We also tried the Axtremex Micro SSD with Mac OS X on an Apple MacBook Pro (Mid-2012) running OS X 10.8.3. Here the required kernel extension (USBattachedSCSI.kext) loaded automatically when the Mac sensed a suitable USB 3.0 was plugged in.
In other words, truly plug and play, and no faffing with different ports, extra system drivers and somewhat unintuitive vendor software to make the drive work correctly.
Sequential writes on the Mac were around 430 MB/s and reads now reached as far as 442 MB/s, best case for 20-100MB test data.
Blackmagic Disk Speed Test sets a trickier challenge by sustaining continuous data throughput, to replicate professional video data transfers. The Micro SSD could sustain 395 MB/s of continuous writing, and 433 MB/s when reading.
In short, this is a truly remarkably fast flash drive, and by far the fastest USB 3.0 device we’ve measured in the lab.
Its nearest competitor we’ve tried could be the Elgato Thunderbolt SSD, but that is effectively Macintosh-only due to its Thunderbolt interface. It also showed appreciably poorer performance overall (205/118 MB/s read/writes) while taking a much larger and weighter slab of metal for its case.
By contrast, the more worrying issue with the Micro SSD is that you may accidentally lose it, being so small and low in weight.
By using a Toshiba SSD, the Micro SSD’s internal storage also does not suffer any slowdown with media files, in contrast to the Elgato with its SandForce-based SanDisk internal SSD.
In use, the Micro SSD’s metal case could get a little warmer when stressed by benchmark testing but not worryingly so. In normal use we experienced no heat issues.
The Micro SSD is a long-awaited storage device – a tiny, portable flash-based drive that can approach the kind of performance promised by the USB 3.0 standard, high speed that’s been waiting to be released from modern flash memory. Setup and operation is tricky in Windows, affected by choice of OS version and motherboards, and will usually require additional drivers. Operation in OS X was flawless, making this an easy recommendation for Mac users especially.