Testbed Setup and Evaluation Methodology

Evaluation of DAS units on Windows is done with the testbed outlined in the table below. For devices with a USB 3.1 Gen 2 (via a Type-C interface) connections (such as the SanDisk Extreme 900 1.92TB that we are considering today), we utilize the USB 3.1 Type-C port enabled by the Intel Alpine Ridge controller. It connects to the Z170 PCH via a PCIe 3.0 x4 link..

AnandTech DAS Testbed Configuration
Motherboard GIGABYTE Z170X-UD5 TH ATX
CPU Intel Core i5-6600K
Memory G.Skill Ripjaws 4 F4-2133C15-8GRR
32 GB ( 4x 8GB)
DDR4-2133 @ 15-15-15-35
OS Drive Samsung SM951 MZVPV256 NVMe 256 GB
SATA Devices Corsair Neutron XT SSD 480 GB
Intel SSD 730 Series 480 GB
Add-on Card None
Chassis Cooler Master HAF XB EVO
PSU Cooler Master V750 750 W
OS Windows 10 Pro x64
Thanks to Cooler Master, GIGABYTE, G.Skill and Intel for the build components

The full details of the reasoning behind choosing the above build components can be found here.

Evaluation involves running synthetic benchmarks such as ATTO and CrystalDiskMark. We also process custom test-suites (transfer of a set of photographs and video files) from a RAM disk on the testbed. Finally, we also run PCMark 8's storage bench on the external device.

The power consumed by the bus-powered device is measured using the Plugable USBC-TKEY interposer. The USBC-TKEY was plugged into one of the Thunderbolt 3 / USB 3.1 Gen 2 Type-C ports enabled by the Alpine Ridge controller. While the USBC-TKEY acts as a transparent interposer for the host's port, it is connected to a Ubuntu system for data gathering purposes via its micro-USB port. The power consumption is tracked while CrystalDiskMark processes its traces.

The Extreme 900 turned out to be a very interesting DAS unit to review. In our initial trials on the Skylake testbed (specified above), the performance numbers turned out to be very inconsistent. While performance was definitely better than any USB 3.0 flash drive for most tests, there were a few with very disappointing numbers. Assuming that it was a compatibility issue for the ASM1352R with the Alpine Ridge controller, we tested out on our Haswell testbed with an ASRock PCIe card (sporting an ASMedia controller). The results were similar. To complicate matters further, it turned out that none of our testbeds could process the PCMark 8 storage bench on the drive. All attempts failed with a workload initialization error.

While trying out various trials, we decided to completely get rid of any partition information on the drive. Using 'diskpart', 'select disk X' and 'clean' commands, we reinitialized the drive and formatted it afresh in exFAT (the drives had originally come pre-formatted in exFAT along with SanDisk's software encryption app). After this process, the PCMark 8 storage bench started working without issues. Benchmark numbers from ATTO and CrystalDiskMark also became consistent from run to run.

Introduction and Usage Impressions Direct-Attached Storage Benchmarks
Comments Locked


View All Comments

  • Chaitanya - Monday, April 11, 2016 - link

    Would have liked to see internals of the drive.
  • Ethos Evoss - Tuesday, April 12, 2016 - link

    What bout TRIM ? SSDs via usb doesn't support it .. so SSD will degrade ...
  • jji7skyline - Thursday, April 14, 2016 - link

    Don't some SSD controllers have TRIM function built in?
  • Ethos Evoss - Thursday, April 14, 2016 - link

    Not really
  • jameskatt - Saturday, May 7, 2016 - link

    Yes. The SSDs from OWC don't need TRIM.
  • chlamchowder - Monday, April 11, 2016 - link

    This is about $200-300 more expensive than a 2 TB SATA SSD. I guess the price is fair if you absolutely need that capacity and speeds higher than what USB 3.0 gives.

    Also, at $800 this SSD costs more than top-of-the-line GPUs from AMD and NVidia.
  • MattMe - Monday, April 11, 2016 - link

    What has this got to do with GPUs?
    Why does it seem as though everyone on this site is only interested in graphics cards? The product being reviewed here is not even remotely aimed at the gaming market.
    Have I missed something, or am I finally the only normal person on a forum?
  • nandnandnand - Monday, April 11, 2016 - link

    It's overpriced storage for a niche market.
  • dontlistentome - Tuesday, April 12, 2016 - link

    Probably not overpriced for the niche it's aimed at....
  • Mattly - Monday, April 11, 2016 - link

    LOL if your the only person on the forums that you consider normal perhaps you should question why you are the only one?

Log in

Don't have an account? Sign up now