Medical OEMs see value in optimizing the right flash technology to ensure host architecture compatibility while meeting application workload requirements. During the design process, manufacturers of medical products undergo long engagement processes with multiple part suppliers. The purpose of these engagements is to ensure that each embedded part will not only work for the application, but also meet the workload and environmental requirements.
However, supplier engagements can be lengthy and complex. As a result, medical OEMs may opt to purchase off-the-shelf parts, particularly when the part is perceived to be a commodity item. This is often the case with flash memory, which is normally selected based on specifications such as type of flash, memory capacity, and form factor.
Because flash memory is widely available in a variety of form factors for consumer electronics, many OEMs assume they can proceed without a customized solution. However, in doing so, OEMs may overlook considerations such as workload (the frequency of reading and writing large amounts of data to memory), power management issues (dirty power, power cycling, power failure), and environmental conditions (temperature, vibration).
These factors can lead to data corruption and other errors in the field, while reducing the reliability and lifespan of the flash storage. For medical OEM products, which can have a life cycle of 3–5 years or longer, compared with 6–18 months for consumer applications, this can cause failures in the field and reduce the overall life of the product.
Many industrial OEMs purchase flash storage devices over the Internet only to discover at the launch of the product that there were unexpected issues due to inaccurate assumptions about the environment and workload requirements.
This can lead to severe consequences for users. In the medical industry, for instance, for data storage to be HIPAA-compliant, it needs integrated transmission security, with encryption hardware that helps to provide this security. Issues of shock and vibration could lead to the unexpected compromising of patient records.
Given the critical role in storing mission-critical data, the majority of industrial flash storage solutions require some level of customization to adequately meet workload requirements in real-world industrial scenarios.
All flash storage has a finite life, depending on how well it is managed and the workload requirements. To optimize and extend the life of a flash storage device, therefore, careful consideration must be given to how data is written to the device.
Writing to flash is the process of prepping the blocks of flash and then programming new data to the flash blocks. However, new data cannot be saved to flash until the old data is first erased. Due to the nature of flash storage, only a finite number of programming and erasing cycles can be performed before wear renders it unreliable to store data. In addition, some flash media is not used evenly, further reducing the life of the device.
Fortunately, there are options to extend the life of a flash device, including reducing unnecessary copying of files or downloading of data, consolidating writes, wear leveling techniques, and even selecting whether the data is written sequentially or randomly.
If an OEM misjudges or misunderstands the workload requirements, there are implications for the storage. It could be as simple as unexplained errors in the field, or it could be a situation where flash memory is wearing out much faster than they realize.
An important flash storage customization option involves mechanical ruggedness. Is the application subjected to unusual amounts of vibration? Does the typical operating environment exceed even standard industrial storage parameters?
Although industrial flash storage is designed to be rugged, different applications have different operating requirements. Customizing the mechanical ruggedness of the storage can alleviate concerns about failures associated with operating conditions.
One of the best ways to ensure that a storage device will work as expected in operating conditions is to partner with a manufacturer who offers testing reliability services. Companies such as Delkin Devices, for example, offer design verification testing, ongoing reliability testing, and even accelerated lift testing to simulate long-term operating conditions at its manufacturing facility in San Diego, CA.
Having a power issue is one of the more common real-world scenarios for industrial flash storage. Power issues can include dirty power, excessive power cycling, and unexpected power failures. When power is lost during a write operation, it can cause data loss. This is because the data that was being written to the storage was not completely saved.
Although only a small amount of data may not have been written when a power failure occurs, it can cause significant ongoing problems, including fatal corruption of the entire system. It can also cause inefficient use of memory capacity, which can dramatically shorten the lifespan of the embedded flash storage.
Taking steps to reduce external sources of power loss is important for mitigating the risk of power failures. However, power failures can still occur, so internal protections are essential for reducing the risk of data loss. For flash memory systems that handle critical data, that means built-in power loss controls, including systems for monitoring power supply and the ability to recover data after a power loss that occurs during a write operation.
Dirty power due to outages, brownouts, surges, and power spikes is another concern. This can be particularly problematic in transportation where DC dips below the required threshold, can ultimately confuse the source, and can lead to errors for equipment critical to the operation.
Excessive power cycling to conserve battery life can also become a problem. In some industries where OEM products are utilized in remote locations, the power is cycled tens of thousands of times a year to keep the battery in a sleep mode or to power it off altogether. This can also degrade the performance of the flash memory.
Finally, the operational requirements refer to the manufacturer’s supply chain and how they go about sourcing parts, engaging suppliers, and ensuring that the parts they source will be available throughout the product life cycle.
It is very common for the bill of materials (BOM) of commercial-grade flash storage to be updated without warning, and this is necessary for consumer OEMs because it helps maximize functionality while minimizing price. For industrial OEMs, including medical device manufacturers, however, what is needed above all is consistency and reliability.
There is an even higher standard that can be achieved, which is when the component parts are controlled and locked. This means that once qualified, the flash, controller, and firmware will not change as long as the part number is active. If anything needs to be changed, the part number is changed and that essentially guarantees that the customer is notified and the BOM is updated.
In the short term, off-the-shelf flash storage may have the right specs and cost less than a customized part from a supplier, but there are always hidden costs and risks for the OEM. Flash storage is a critical part for rugged industrial applications, and more manufacturers should engage a supplier from the beginning of the design process to ensure that they get what they need for the entire life cycle of their product.
Medical OEMs are often more focused on designing a high-quality product, and so do not spend much time considering flash storage. But given the critical nature of data in today’s devices, there is too much risk to take industrial flash for granted.
This article was written by Tony Diaz, Product Manager for Delkin Devices, Poway, CA. For more information, visit here .