I ran CrystalDiskMark on my SATA 3 connected Samsung Evo 850 SSD, and it reported a 1839MB/s sequential read speed, and 1676MB/s write speed. SATA 3 has a maximum of 750MB/s and Samsung says at best it would perform at 540MB/s. Is the software wrong, why is it so fast?
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Something is not right there. I am curious if the Seq is supposed to be in bits not Bytes. Still, at that you would be in the 200s– Some DudeDec 31, 2015 at 20:25
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@Tim I would also be curious if any ram caching is being measured if it is not bits / bytes translation.– user493784Dec 31, 2015 at 20:26
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It is best to use a Samsung SSD tool to determine the performance of a Samsung SSD. I honestly wouldn't trust CDM.– RamhoundDec 31, 2015 at 20:27
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@iancnorden ram does seem more likely.– Some DudeDec 31, 2015 at 20:47
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1 Answer
Apparently some of the Samsung SSD use a technology called RAPID mode. As far as I can tell this is basically a huge cache using the PC's memory. The effect you see from this in benchmarking is a dominance of memory transfer speed over SATA transfer speed especially on sequential (and therefor predictable) operations.
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answered Dec 31, 2015 at 20:58
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The Samsung Magician benchmark had similar results. I also checked the RAM usage as the benchmark was running, and it increased at the same time as I started the benchmark, confirming what you said.– MatthewDec 31, 2015 at 21:32