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> we introduce a NoWA (No Write Amplification) pattern that guarantees SSD WAF = 1, even at full device utilization.

That they got this to work on regular commodity SSDs (from multiple vendors) is very impressive.

Very interesting indeed. They mention a very simple rule of thumb (not new to this work AIUI but still worthwhile) that suggests arranging data into blocks that will all be discarded in bulk at the same time. Doing this is generally already enough to make a dent into write-amplification.

The end goal of the NoWA write pattern is conceptually similar to what you described, in the sense that NoWA tries to increase the chance that data becomes invalid together inside the SSD, which is also what mechanisms such as TRIM try to facilitate. The NoWA pattern is more about proactively aligning the application-level GC behavior with the SSD’s internal GC behavior, such that the SSD has little or no valid-page movement left to do internally.

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