FEATURE EMBEDDED ELECTRONICS


How to get the best performance out of SSDs


Matt Lundberg, technical lead of industrial IoT at Impulse Embedded explores key considerations for selecting the optimum SSD for an Industrial or embedded system


before we reach for our wallets in excitement, with increased storage capacity comes decreased reliability. Storage capacity is dictated by the


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hoosing the correct Solid State Drive (SSD) for your industrial computing


or embedded system application is key to maintaining a successful, reliable installation. With various form factors, durability,


and security features, the selection does not always boil down to price, and choosing which SSD is right for your single board computer or fanless PC can mean the difference between an installation truly fit-for-purpose, or one with the potential to under deliver, or worse, fail completely. Form factor is perhaps the first


consideration when choosing an SSD for an industrial or embedded computing application. It’s not just about space - or the hole the SSD is going into - with different form factors come different interfaces, and different interfaces provide various features that may or may not be applicable to your industrial or embedded computing installation. For instance, if we look at the 2.5” SSD


form factor, which is arguably the most commonly available in ready-to-go integrated embedded computers, this offers a number of benefits: due to its ubiquitousness, availability is never normally an issue, and these large capacity drives are easy to install. They support most (or even all) flash technologies, such as TLC, MLC and SLD, often support extended temperature ranges from as low as -40°C to 85°C, and also provide options for resilience technologies, which protect your data and operating system from power


34 MARCH 2021 | ELECTRONICS


instability or outages. If you would prefer your SSD to be


installed using a more discreet method, perhaps in an effort to reduce overall system footprint, or are using an embedded computer board with a single power source, then MSATA or M.2 (MSATA's updated equivalent) could be the best option. These drives fit parallel with the board, taking their power directly from the SBC/embedded PC, whereas 2.5” SSDs require separate cabling for data and power, which take up valuable room in embedded applications with space limitations. If supported, NVMe technology can allow for up to 10x faster read times of M.2 SATA devices, due to their use of the more efficient PCIe bus, but this technology does not have the more comprehensive boot support that SATA drives can offer. The flash, or NAND, type dictates speed


and reliability parameters, but it’s not just a case of choosing the fastest and most reliable. Not only are these two maximums not available in the same NAND type, but the NAND type you’re able to use is dependent on the amount and frequency of data being written to and read from the SSD. The acronyms SLC (Single-Level Cell),


MLC (Multi-Level Cell), and TLC (Triple- Level Cell), dictate the storage capacity for each type of SSD NAND Flash. It’s as you imagine: the more levels, the higher the storage capacity, with Triple-Level Cells (TLC) providing the most. TLC SSDs are also generally the cheapest, but


number of levels in the SSD Flash cell and is governed by the reliability one needs for a project. For critical applications, as an example, it would be pertinent to opt for a more expensive single-level cell, which trades storage capacity for reliability. For less critical applications, you may choose a multi or triple layer cell, which provides far more storage capacity at the potential cost of lower reliability. Environmental factors are one of the


last things to mention, but no less important. There is a general rule of thumb as to what is considered “normal” temperature, which falls somewhere in between 0°C and 50°C, with devices sitting in environments that fall outside of that range generally requiring wide or extended temperature capabilities. And it’s not just the ambient air temperature that needs to be factored into the calculations - in scenarios such as devices in direct sunlight, the temperature inside the actual enclosure will ramp up due to heat exchange from other components - these are all environmental aspects which need to be thought about during the planning stage. Fortunately, many of the


manufacturing partners available from Impulse Embedded offer SSDs with these wide temperature capabilities, along with conformal coating, a varnish-style covering applied to components such as PCBs to protect from high humidity or moisture ingress. A full understanding of the end application will ensure the selection of the most appropriate drive. Power struggles.


Impulse Embedded www.impulse-embedded.co.uk


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