Burn-In Speed Testing

A prospective VIUD buyer recently asked me this question:

How well are the read/write times in comparison to market stock times? I have a SanDisk, but for the life of me they don't post read times, and it slows down in the middle of large projects. ... When it gets hot my progress slows down by a whole addition hour.

An interesting question that I didn't have the exact answer to. I've done a lot of basic, short-term speed testing and a couple of very long (weeks) burn-in tests for error checking, but no tests to see if the USB speed varied over a long term or to measure how hot the VIUD gets.

Testing

The basic setup was to just continually write to a VIUD over a period of about a day (continually copy a 4GB file to the drive) and do a couple of speed tests over that period to see if there was any variation. The continuous writing to the drive was paused while the speed tests were performed.

Since the original question may be related to drive temperature I also measured the temperature of the case. The tests were done for both an Aluminum (32GB) and Titanium (256GB) drive.

Results

Results are shown the below tables.

Time	Case Temp	Read Speed	Write Speed
0 hr	23°C	155.4 MB/s	98.1 MB/s
0.5 hr	27°C
2.5 hrs	33°C
5.7 hrs	35°C
8.5 hrs	37°C	157.0 MB/s	89.2 MB/s
21.3 hrs	37°C	156.8 MB/s	89.3 MB/s
28.3 hrs	36°C	155.1 MB/s	87.2 MB/s

Burn-In Speed Test for Titanium 256GB VIUD

Time	Case Temp	Read Speed	Write Speed
0 hr	22°C	142.1 MB/s	28.5 MB/s
4.2 hrs	30°C	142.9 MB/s	28.6 MB/s
17.5 hrs	28°C	143.5 MB/s	28.3 MB/s
27.3 hrs	29°C	141.2 MB/s	18.1 MB/s

Burn-In Speed Test for Aluminum 32GB VIUD

In read/write speeds are the sequential speeds obtained from the CrystalDiskMark benchmarks. While there is some variation in the read tests it is within what we would expect the normal variation to be. The write tests show a small drop (9%) in the write speed for the Titanium drive. For the Aluminum drive the last write speed test shows a significant (36%) drop in write speed although I'm not sure I believe that data point or not as the HD Tune Pro results showed no significant speed decrease in any test for either VIUD.

For the temperature testing the ambient temperature was around 20°C for all tests. The temperature was measured where it was the highest value on the drive which tended to be the USB connector.

I also did some quick tests on a Sandisk Extreme 16GB USB drive. Temperatures were similar to the Titanium VIUD and no speed degradation was observed.

In terms of qualitative results, the Titanium VIUD gets very warm but not uncomfortable to the touch, similar to a normal USB drive. The Aluminum VIUD gets just a little warm to the touch.

Theory

The potential reason a typical consumer USB drive might overheat and a VIUD might not can be explained by looking at the thermal conductivities of the relevant materials.

Material	Thermal Conductivity
Air	0.025 W/mK
Epoxy	0.3 W/mK
Titanium	20 W/mK
Aluminum	205 W/mK

In a consumer USB drive the circuit board is surrounded by air trapped inside the case which has a very low thermal conductivity thus trapping the heat near the board and causing to it to reach a high temperature. In a VIUD drive the circuit board is surrounded by epoxy which has 10x the thermal conductivity than air which enables it to direct the heat away from the board and into the metal case and air. In addition, the VIUD drive has the USB metal connector in close contact to the metal plug which further helps conduct the heat away from the USB.

Discussion

Compared to a normal USB the Titanium VIUD reached a similar temperature on the USB metal connector (37°C). How this translates to the interior circuit board temperature is unknown...we would expect the epoxy encased VIUD to be somewhat cooler than an air encased USB but by exactly how much would require more advanced temperature modeling.

The Aluminum VIUD was noticeably cooler on the USB metal connector (30°C) and would be the choice if long term reading/writing and overheating of the USB was a concern.

The VIUD Store is Now Open!

After a month of preparation and worrying about all the little details I'm happy to announce that the VIUD store is now open at:

https://store.viud.net

So go and check it out and even if you don't decide to buy anything feel free to leave me comments and suggestions!

Updated USB Specifications

Last week was spent updating the VIUD specifications on the new store site which includes a number of values related to the USB (read on for an explanation of each benchmark):

	16 GB	32 GB	64 GB	128 GB	256 GB
Usable Capacity	15,961,546,752 bytes	31,651,479,552 bytes	62,911,414,272 bytes	125,818,503,168 bytes	253,121,003,520 bytes
File System	FAT32	FAT32	exFAT	exFAT	exFAT
HD Tune Pro Benchmarks
Read	106.5 - 116.7 MB/s	114.2 - 127.9 MB/s	119.9 - 130.7 MB/s	181.2 - 193.3 MB/s	56.0 - 146.8 MB/s
Average Read	111.7 MB/s	121.9 MB/s	123.5 MB/s	187.7 MB/s	142.1 MB/s
Access Time	0.889 ms	0.973 ms	1.16 ms	0.747 ms	0.811 ms
Crystal Disk Mark Benchmarks
Read Seq Thread	121.6 MB/s	130.1 MB/s	133.3 MB/s	208.8 MB/s	149.2 MB/s
Read Rnd Thread	16.4 MB/s	14.3 MB/s	14.1 MB/s	6.03 MB/s	22.1 MB/s
Read Seq	119.8 MB/s	127.6 MB/s	131.6 MB/s	205.4 MB/s	146.6 MB/s
Read Rnd	15.0 MB/s	13.3 MB/s	13.6 MB/s	5.47 MB/s	19.2 MB/s
Write Seq Thread	24.2 MB/s	34.8 MB/s	38.2 MB/s	132.5 MB/s	94.1 MB/s
Write Rnd Thread	0.051 MB/s	0.097 MB/s	0.69 MB/s	0.224 MB/s	1.37 MB/s
Write Seq	22.4 MB/s	25.6 MB/s	17.8 MB/s	129.8 MB/s	22.6 MB/s
Write Rnd	0.054 MB/s	0.055 MB/s	0.81 MB/s	0.0048 MB/s	1.07 MB/s
USBFlashBench Benchmarks
Read	116.70 MB/s	124.93 MB/s	127.54 MB/s	206.48 MB/s	131.13 MB/s
Write	22.72 MB/s	29.40 MB/s	32.89 MB/s	133.83 MB/s	55.93 MB/s
Link	157023	157008	157022	157018	157011
4GB File Copy
Copy	2:38.3 (24.1 MB/s)	1:49.5 (34.8 MB/s)	1:42.1 (37.3 MB/s)	0:30.2 (126.3 MB/s)	0:44.8 (85.2 MB/s)
Read	0:33.4 (114.1 MB/s)	0:31.2 (122.1 MB/s)	0:30.6 (124.6 MB/s)	0:18.4 (206.9 MB/s)	0:28.8 (132.7 MB/s)

The VIUD's usable capacity is slightly less than the stated capacity which is typical of just about any mass storage device. Part of the overall device's drive space is taken up by the file allocation table which takes more space on larger drives. The other part, however, is just due to the USB board manufacturer using a slightly smaller size than stated. Perhaps this is due to a technical reason or, more likely, an economic one.

HD Tune Pro is a basic disk benchmarking and testing application. Unfortunately the write tests don't seem to work on newer operating systems but the read and error tests do give a nice visual display. I'd like to point out the low minimum read speed for the 256 GB VIUD which can be easily seen in the following graph:

VIUD 256 GB HDTunePro Read Benchmark

All other VIUD capacities have a roughly flat graph for the blue line but the 256 GB model has much slower read speeds at exactly 32 GB intervals for whatever reason.

CrystalDiskMark is another basic drive benchmarking tool that outputs several read and write tests:

• Seq Thread = Sequential read/write, 128 KB block size with multiple queues and threads
• Rnd Thread = Random read/write, 4 KB block size with multiple queues and threads
• Seq = Sequential read/write, 1 MB block size with single thread
• Rnd = Random read/write, 4KB block size with single thread

USBFlashBench is a simple tool that tests multiple block read/write sizes and then uploads the results to a website and creates nice graphs like:

USBFlashBench Results for the 256 GB VIUD

Finally, the 4GB file copy test is simply the time it takes to copy a 4 GB (4,000,000,000 bytes) file composed of random content to the VIUD and the time it takes to read it back. Due to caching we have to make sure to unplug the VIUD after the write test and then plug it back in to do the read test.

Product Shots!

Work on creating the VIUD store started last week and I'm already well on my way to getting it finished. I decided to go with Shopify as it seems to be a good sized Canadian online e-commerce system with the features I need.

I've spent the better part of the last week taking and preparing product shots of all the various VIUD models for use in the store. There are a lot of good online guides for taking product shots but to summarize what I've used:

• Niken D90 camera with SB-600 flash
• Small light tent
• Piece of white paper over the flash to disperse flash and soften shadows
• A few extra lights to get better shadow and reflections (some "real" camera lights would be very nice but I've made do)
• About half-zoomed in on the lens
• Auto color balance on the camera
• Manual mode on the camera with a high aperture (F20) for a larger depth of field
• Adjust the exposure time and bias to get a good picture (white background without too much shadow)
• Adjust the picture's brightness, contrast, and saturation afterwards to get a realistic and good looking image

The shots turned out pretty good and I think they can speak for themselves!

Getting Closer...

So my summer vacation is unfortunately over and I'm getting back into the finishing stages of the VIUD preparation. All I can do before actually selling them is to do the coating of all the USB boards I currently have.

Through all the various testing I've done, mainly the shock testing, I've narrowed down a good combination of coatings and epoxies that seems to maximize the durability of the USB. I start with two layers of Silicon conformal coating.

Silicon Conformal Coating a USB

This is thin, flexible coating that gets into all the small nooks and crannies on the circuit board and even by itself seems to help a lot in minimizing damage caused by shock. Each coat requires at least a day to dry out.

Drying Out the Conformal Coating

Once the two conformal coatings are dry it is time for another two coatings of a thicker and more flexible insulating coating.

Coating a USB in Insulating Varnish

This gives the USB circuit board a considerably thicker and flexible coat to help absorb even more shock. It also helps prevent epoxy from leaking through the USB connector and making a considerable mess which is difficult and time consuming to clean up. Like the conformal coating each insulating coating takes a day to dry.

Drying Out the Insulating Coating

Next step is to just create an online store and actually start selling things! 

Week(s) in Review: 29 April 2016

In the past month or so I've finally managed to complete finishing the Titanium bases and have all bases laser engraved with the VIUD logo and serial number and they're looking great!

 I also experimented with custom logo/text and it worked out very well but the price point to have it done is unfortunately large enough to make it only worthwhile for larger quantities (say 10 or more).

Custom Logo and Text Example

There's not much left to do! I can conformal coat all the USB boards and then find, design and setup an online store. Unfortunately, it looks as though I may be away all summer which will put another delay in the VIUD progress but it won't be long now!

Week(s) in Review: 14 March 2016

Its been a busy month for me in other projects, particularly with the release of the Thieves Guild DLC for Elder Scrolls Online. 

Besides a little bit of label preparation the only other news to note is that the anodized cases have arrived and they look great!

Titanium VIUD (Left) and 4 Anodized Aluminum Colors

Next steps are to polish the Titanium bases so I can have the VIUD logo and serial number Laser engraved. After that we are ready to start actually selling things!