OEMs want to answer the question, “How long will this SSD last?” in some time unit like hours or years.
They want the parameters of that answer to be calculated similarly between vendors so apples-to-apples comparisons can be made. This is difficult if not impossible to accomplish because the two most significant variables in the endurance calculation are usage model and write amplification.
While OEMs may be able to monitor their usage model in terms of data written from their system to the controller on the SSD, they will not know how the SSD controller manages NAND flash on the back end (this is the write amplification factor).
This Western Digital white paper, written by Silicon Systems, examines the basics of NAND flash and some algorithms SSD vendors use to manage it. It also proposes an endurance metric that separates the parameters the SSD manufacturers control from those the system OEM can control.
- NAND flash basics
- NAND trends
- SSD reliability
- Equations, calculations and measurements
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