Tag Archives: SSD

ATS Wind Tunnels Designed for SSD and PCIe Thermal Characterization

As was outlined in an earlier article on this blog, it is critical for manufacturers to characterize solid-state drives (SSD) to establish performance parameters in real-world conditions. The previous article explained that SSD experience higher failure rates and reduced lifespan when temperatures increase beyond the standard operating range of 30-40°C.

Wind Tunnels
ATS designed wind tunnels for companies looking to characterize solid-state drives in the PCIe form factor, as show above. (Wikimedia Commons)

Testing processes for SSD are similar to those used for characterizing typical semiconductors. A wind tunnel provides a consistent, controlled, and repeatable environment for data collection and sensors, thermocouples, and an analog-to-digital capture system allows engineers to measure performance when the SSD is impacted by external factors.

ATS designs and fabricates research-quality wind tunnels that can be used for characterizing SSD. The wind tunnels give engineers control over air temperature and velocity. Closed-loop wind tunnels can create environments with temperatures as high as 80°C to provide stressed conditions well above standard operating temperatures. The manufacturer can use this data to set reference points for different environments, such as in 1-U telecommunications chassis or large server boxes.

Recently, ATS has worked with two of the industry’s largest producers of SSD to design wind tunnels that could be used for characterizing drives in PCIe applications. PCIe (peripheral component interconnect express) cards are high-speed serial computer extension cards that connect peripheral devices to the motherboard. In addition to SSD, these cards can be used for graphics processors, Wi-Fi, or other hard drives.

ATS wind tunnels can be used to test airflow and thermal performance for components and boards, as shown in this smoke flow visualization test over a maxiFLOW™ heat sink. (Advanced Thermal Solutions, Inc.)

One of the wind tunnels was a standard, open loop CWT-107™. It can produce uniform and homogeneous flow, up to 5.5 m/s (1100 ft/min) within the wind tunnel’s test section due to its polynomial shape and internal flow management system, which features honeycombs and screens to break up turbulence. The wind tunnel can be operated either vertically or horizontally and the customer chose to use it lying down.

In fact, the customer was very creative in its use of the wind tunnel. A customized cart was built for the wind tunnel to be bolted to and then the cart was wheeled into a large environmental chamber where temperatures could be raised to test levels. The SSD being characterized was a PCIe card with memory installed. There was no fan for the memory and the memory had no shielding or housing.

The customer placed its PCIe-based SSD flat in the test chamber. Power was pulled through the test ports included in the test chamber of the CLWT-107™ (as shown below).

While the wind tunnel was bought for testing SSD, it could be used by the customer to test any electronic component or board.

The second customer purchased a CLWT-115™ closed-loop wind tunnel. In this case, the application required the SSD to be powered through the PCIe back plane, so ATS custom-designed slots in the test section to fit the PCIe form factor. The slots allowed the SSD to remain inside the test section and be connected to a motherboard residing outside the wind tunnel (see below).

Again, the wind tunnel could be used to test any PCIe cards, not just SSD, if the customer desired, as there were also fillers created for the slots to allow the wind tunnel to be used when testing other devices.

The second customer did all of its air velocity and temperature testing in the CLWT-115™, rather than using an environmental chamber like the first customer, because the wind tunnel has a self-contained heating unit that heats air while it circulates during testing.

Wind tunnel controllers and ATVS systems were also purchased by both customers to ensure accurate data collection. The first customer bought an ATVS-NxT™, which is a fully portable scanner that operates with an embedded PC and touch screen control, while the second customer bought the ATVS-2020™, which allows single- or multi-point measurement of both temperature and velocity, and a CLWTC-1000™, which automatically controlled the airflow and temperature through the test chamber.

Both come with Candlestick sensors to control the air velocity in the wind tunnel and thermocouples to control the temperature.

One of the customers also requested a custom, rugged sensor to avoid damage through multiple uses. ATS was able to adapt one of its handheld surface probes, a stainless-steel probe with a pointed tip for exact positioning of the sensor on the desired spot, by reducing the length and designing a custom port that would hold the sensor in place.

SSD are gaining traction in the market, with major hard drive manufacturers and the companies that utilize them both making the switch to solid-state technology. This means that thermal characterization of SSD and thermal management systems deployed to dissipate the heat of these drives are going to be of increasing importance in the coming years.

Using research-quality wind tunnels gives manufacturers a leg up in determining how their drives will perform in different real-world environments and makes the process of SSD characterization easier for users. By working with ATS, companies can tailor their wind tunnels to their specific applications and can be assured of the accuracy of the data that they collect.

Learn more about ATS wind tunnels, sensors, and the entire line of next-generation thermal test instruments at https://www.qats.com/Products/
Instruments. If you have questions about any products or ATS thermal testing services, email ats-hq@qats.com.

For more information about Advanced Thermal Solutions, Inc. (ATS) thermal management consulting and design services, visit https://www.qats.com/consulting or contact ATS at 781.769.2800 or ats-hq@qats.com.

Why is thermal characterization of SSD important?

Thanks to faster boot-up times and enhanced reliability and performance, solid-state drives (SSD) have grown in popularity with consumers in the past decade. From laptops to portable hard drives to telecommunications applications, solid-state drives are eclipsing hard disk drives, particularly as the price of SSD technology lowers, making it more cost-effective for system designers.

What makes the SSD different? Solid-state drives have no moving parts. There is no mechanical arm to read and write data. Instead SSD use embedded processors to control the processes related to storing, retrieving, caching, encrypting, and cleaning up data.

Thermal Characterization of SSD

Apple is one of many laptop companies that have turned to solid-state drives for laptops because of improved boot times and better battery efficiency. (Wikimedia Commons)

As explained by Storage Review, “Conversely, a hard disk drive uses a mechanical arm with a read/write head to move around and read information from the right location on a storage platter. This difference is what makes SSD so much faster. As an analogy, what’s quicker? Having to walk across the room to retrieve a book to get information or simply magically having that book open in front of you when you need it? That’s how an HDD compares to an SSD; it simply requires more physical labor (mechanical movement) to get information.” [1]

Consumers and engineers alike are turning to SSD and that has made a number of companies jump into the market, although, according to a recent report that counted global sales through 2016, Samsung (21 percent) and Kingston (16) percent remain the largest retailers of SSD in the world. All the other companies listed, including Intel, SanDisk, and Toshiba, all had percentages in the single digits. [2]

The benefits of SSD are well-known: System boot times that are typically 1/3-1/4 of HDD, half of the power draw for longer battery life, much larger storage capacity, reduced noise during use, and greater mean time between failure (MTBF).

One area of importance for SSD, which is another byproduct of no moving parts, is that they generally produce less heat than HDD. For instance, you are less likely to burn your lap while working on your laptop if it has a solid-state drive. Thermal issues remain for SSD, as they do for any electronic device, but compared to HDD they have fewer cooling requirements. [3]

A recent study out of Carnegie Mellon University (Pittsburgh, Pa.) in collaboration with Facebook, Inc. analyzed the reliability of flash-based SSD. One of the external factors that the researchers considered was temperature. In examining three distinct groups of SSD in a Facebook data center, the study described similar failure rates at a range of 30-40°C, but the failure rates varied greatly as temperatures increased beyond that operating range. Failure rates are explained in the following tables. [4]

This chart from researchers at Carnegie Mellon demonstrates the instability that temperature spikes cause in SSD performance. [4]

The researchers concluded, “In general, we find techniques like throttling, which may be employed to reduce SSD temperature, to be effective at reducing the failure rate of SSDs. We also find that SSD temperature is correlated with the power used to transmit data across the PCIe bus, which can potentially be used as a proxy for temperature in the absence of SSD temperature sensors.”

Temperature is an increasing factor for SSD. Like the rest of the electronics industry, engineers are designing SSD to handle more chips, more channels, more cores, and more controllers to handle a greater level of processing capability. A study from the Computer Architecture and Memory Systems Lab at the University of Texas – Dallas (UT Dallas), presented at HotStorage 2014, reported that there were 64 times as many chips and channels in SSD as there were just 12 years before. Just like the Carnegie Mellon study, the UT-Dallas researchers determined that “device-level protection mechanisms dynamically reduce heat output.” [5]

This chart from UT-Dallas shows the performance degradation that comes from overheating of SSD. [5]

The UT-Dallas study concluded that overheating led to malfunctions in the SSD and that devices with larger data sizes reached the overheating point quicker. According to the report, there was “significant performance degradation at the overheating points” and that overheating and its requisite power throttling “hinder SSD from integrating more resources.” This problem, the study concluded, was “holding back state-of-the-art SSD from achieving potential performance gains.”

As SSD continues to gain a stronghold in the market, including Intel’s recent announcement that it was going to accelerate the deployment of its SSD technology throughout its product line to “enhance user productivity and mobility while reducing IT total cost of ownership,” [6] it is obvious that thermal characterization of SSD and thermal management of systems with SSD are primary concerns for the industry.

There is also a real cost to bad data and SSD are not removed from that risk. From the CPU to the PCB to SSD storage, inaccuracies and outright errors adversely impact device reliability and system design. One model that is commonly used in the characterization of SSD and other data storage products is the Arrhenius Model:


This reliability model has temperature as a key component. These models can be used via pen and paper, computer modeling or on a spreadsheet. But is the Arrhenius model a good model for NAND (negative-AND) flash memory?

Data presented at the Flash Memory Summit in 2014 by IBM showed that reliability models such as Arrhenius are not necessarily accurate for characterizing SSD. Indeed, such a model can end up creating a correct match for just two data points. The presentation recommends that acceleration models be validated. In addition, it is recommended that it is best to test a full device and that doing so will best allow measurement of the total behavior. [7]

The Storage Networking Industry Association (SNIA) also released a test methodology, test suite, and reporting format for SSD to ensure the accuracy and reliability of the data being reported. [8]

Measuring the thermal characteristics of SSD is similar to the process of characterizing a standard semiconductor. A typical test setup for characterization would include a closed-loop wind tunnel, preferably with heater, sensors, thermocouples or RTD and an analog-to-digital capture system or hot wire anemometer. A closed-loop wind tunnel with heater provides an environment for controlled temperatures from ambient to 85°C or more (although most testing will take place lower than 70°C to avoid damaging the device). Thermocouples or sensors will give important data about the junction temperature of the machine as it is in operation within the system and instruments and sensors can be incorporated to see how the SSD reacts to external factors.

It is critical that thermal management is considered not only in the design phase, but that the products are tested to determine the impact of temperature on date storage to avoid errors, lost information and device failure. To make sure that the data is accurate and reliable and to save time and money in the long-run, it is imperative to use research-quality instruments during the test phase.

As an article from Qpedia Thermal eMagazine explained, “Small errors in temperature and air flow measurements can have a significant effect on reliability predictions. The origin of these errors lies in the measurement process or the use of inaccurate instruments.”

The article continued, “Accurate and high-quality instruments are not only essential for any engineering practice, their absence will adversely impact reliability predictions of a product at hand. No company wants to have its products returned, especially because of thermally induced failures.” [9]

Advanced Thermal Solutions, Inc. (ATS) has an array of state-of-the-art thermal instruments that can be used to study the impact of temperature on SSD performance from closed-loop and open-loop wind tunnels to highly-accurate, portable hot-wire anemometer systems, such as the ATVS-2020 (pictured below), as well as next-generation sensors, including the handheld surface probe that is designed for measuring the surface temperature of solids.

Thermal Characterization of SSD

The ATVS-2020™ Automatic Temperature & Velocity Scanner is a patented, multi-channel hot wire anemometer system for single or multi-point measuring of air temperature and velocity. (Advanced Thermal Solutions, Inc.)

Learn more about the instruments that ATS has to offer for SSD thermal characterization in the video below:

1. http://www.storagereview.com/ssd_vs_hdd
2. https://www.kitguru.net/components/ssd-drives/matthew-wilson/kingston-samsung-and-are-dominating-the-global-ssd-market/
3. http://www.tomsitpro.com/articles/enterprise-ssd-testing,2-863.html
4. https://users.ece.cmu.edu/~omutlu/pub/flash-memory-failures-in-the-field-at-facebook_sigmetrics15.pdf
5. https://www.usenix.org/sites/default/files/conference/protected-files/hotstorage14_slides_zhang.pdf
6. https://www.intel.com/content/dam/doc/white-paper/intel-it-mobile-computing-ssd-accelerating-deployment-paper.pdf
7. https://www.flashmemorysummit.com/English/Collaterals/

8. http://www.snia.org/sites/default/files/SSS_PTS_Enterprise_v1.1.pdf
9. https://www.qats.com/cms/2013/05/28/why-use-research-quality-instruments/

For more information about Advanced Thermal Solutions, Inc. (ATS) thermal characterization capabilities, visit https://www.qats.com/Consulting/Lab-Capabilities or contact ATS at 781.769.2800 or ats-hq@qats.com.