Storage Evolution Driving Growth of System-Level Test

By Colin Ritchie, Vice President, System Level Test Business Unit, Advantest,
and Scott West, Marketing Manager, System Level Test Business Unit, Advantest

Thanks in large part to the booming mobile market, global demand for storage capacity continues unabated. Gartner indicates that solid-state drive (SSD) shipments are on pace to top 370 million units by 2020, while Research & Markets forecasts that the client SSD market alone will grow at a compound annual rate (CAGR) of 36 percent between 2017 and 2021. With this growth comes an increased drive for performance, requiring implementation of new/updated storage protocols.

Currently, the market supports three primary storage protocols. Serial ATA (SATA) and Serial Attached SCSI (SAS) are still in use – the latter, for enterprise applications in particular – but there is a migration towards the newer PCI Express protocol. Increasingly, SSD makers are choosing the latest incarnations of PCI Express: PCIe Gen 3 and the forthcoming Gen 4. In addition, often used with PCIe is Non-Volatile Memory Express (NVMe), a storage interface/protocol developed especially for SSDs by a consortium of prominent vendors.

This shift toward newer, faster protocols creates an associated need for improved test speed and accuracy. Driven by these and other associated demands, the test industry is moving up the value chain, from component-level to module-level to system-level testing. System-level test (SLT) is not only different from classical component test, but also more difficult, creating some key challenges to be addressed.

In-house solutions no longer viable

Storage SLT is still in its infancy, much as memory test was three decades ago. However, an SSD’s state machine has virtually an infinite number of combinations that must be tested effectively without an infinite amount of time available to perform brute-force iterations. While ICs have a set number of vectors or memory patterns to be run, SSDs feature a huge number of constantly changing states – factor in unplanned events (such as power-cycling), and the result is a huge number of cases that are difficult to cover. SSD providers can’t address every eventuality – but they must be able to ship product to their customers with absolute confidence it will work.

Traditionally, storage makers have created their own test solutions in-house because of the high degree of customization required – in addition, no commercially viable solution was available that could meet their needs. However, as the pace of change and growth in the storage market continue to accelerate, these companies have come to recognize that they cannot keep developing their own internal test solutions – they will end up spending more time, money and engineering resources on developing the ability to test their products than they will on developing the actual products. Greater expertise is needed to test the higher performance devices while maintaining a consistent solution across increasing production volumes is. Faster product cycles make this an even more pressing issue.

SSD product lifecycles have collapsed down from two years to as little as six months. In the time it would take for a storage maker to develop its own custom test solution, the product for which it’s intended will have already peaked and be on its way to obsolescence. Reinventing the wheel with each new product is simply no longer viable. Most of these manufacturers have thus made the decision to implement commercial test solutions.

Advantest leading the way in SLT

This creates a substantial opportunity for Advantest. Storage is a market in which Advantest has purposely become a fundamental enabler of growth, as well as a quality arbitrator. The company is committed to helping customers wean themselves away from in-house-developed test solution, with its MPT3000 platform allowing customers to focus on their core competencies. As an example, an executive with a leading SSD supplier that previously focused on traditional flash memory components, recently acknowledged his company’s decision to align itself with Advantest. They needed a partner they could depend on to develop the volume of test solutions needed to meet customer demand in the face of collapsing time-to-market (TTM) windows.

The platform strategy Advantest has refined in the ATE industry applies directly to system level test. By developing modular components for the common platform, both standard solutions as well as targeted custom solutions can be configured, cost effectively. When a custom need arises, the platform components provide 80 to 90 percent of the solution, allowing efficient use of Advantest’s expertise to adapt the solution to a specific configuration. Each adaptation extends the platform so storage makers can benefit, through working with Advantest, from their peers’ shared knowledge and experience.

Going back to the shortened product lifecycle, when the TTM window is only six to nine months, missing one design win can greatly impact a storage maker’s business. A three-month delay in the product cycle can translate to a 10-percent market-share hit – e.g., a loss of $100 million from a $1 billion SSD revenue stream is clearly significant! Advantest’s goal is to take test off the table for customers when competing for business – the tester should never be a gating factor in this regard. By implementing the modular MPT3000 platform, they can compete on their product differentiation

Another key challenge storage makers face is of the need for flexibility in terms of manufacturing floor configuration. They spend significant amounts of money building their factories based on their business forecast, customer demand and production plan. However, as we’re seeing increasingly, these plans can change dramatically in a short time, necessitating flexible solutions on their factory floor that can be retooled easily, efficiently and cost-effectively to meet changing customer demand and/or when moving from one product generation to the next. The MPT3000’s FPGA-based test architecture enables quick changeover, maximizing utilization and production output for customers.

Advantest’s portfolio today comprises end-to-end test – from components through modules to systems. The MPT3000 platform is focused on system-level test for the SSD market, and is serving as both a test case, if you will, and a learning platform for further SLT efforts within the company. A previous GO SEMI article delved further into its protocol test capabilities: http://www.gosemiandbeyond.com/applying-flexible-ate-technology-to-protocol-test-and-the-ssd-market/

Other past articles that shed light on Advantest’s system-level test efforts include last issue’s piece on SLT for embedded NAND flash memories – http://www.gosemiandbeyond.com/system-level-test-essential-for-fast-growing-embedded-nand-market/ – and a prior interview with Artun Kutchuk of Advantest Group’s W2BI business, which provides wireless test automation products for the mobile and IoT space: http://www.gosemiandbeyond.com/out-of-the-lab-and-into-the-field-making-iot-device-testing-portable/.

We are interested in learning about the kinds of SLT challenges you face – whether in storage or elsewhere. Please feel free to comment below, or send an email to Scott.West@Advantest.com, to share your knowledge and expertise.