You are just changing the metric of measurement to come to your conclusion. The OP said "throughput is closer to disk that memory" which your own numbers, 20 GB/s vs 500 MB/s vs 160MB/s line up very well with, a ratio of 400:1 vs 3:1. You counter with "characteristic size is closer to memory than disk".
You mention that characteristic size is the crucial parameter, but isn't that only the case when you are only considering a single storage medium? Since you always have memory, wouldn't a caching strategy between memory and SSD provide superior performance compared to only worrying about how the data is formatted while on the SSD?
Overall I would agree that SSD's have similar seek performance to RAM, where you can live with fragmentation, but I think the OP's point that there throughput is barely better than a disk is still valid.
You make a good point about bandwidth--that SSDs are more like disks. However, OP doesn't mention bandwidth, nor is it relevant to his experiment.
What would it mean for "SSD to be like slow memory"? To me, it would mean that both bandwidth and seeks would run proportionally slower. This is why I'm using the "characteristic size" metric--to evaluate that proportionality (and to give it a physical interpretation).
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You are just changing the metric of measurement to come to your conclusion. The OP said "throughput is closer to disk that memory" which your own numbers, 20 GB/s vs 500 MB/s vs 160MB/s line up very well with, a ratio of 400:1 vs 3:1. You counter with "characteristic size is closer to memory than disk".
You mention that characteristic size is the crucial parameter, but isn't that only the case when you are only considering a single storage medium? Since you always have memory, wouldn't a caching strategy between memory and SSD provide superior performance compared to only worrying about how the data is formatted while on the SSD?
Overall I would agree that SSD's have similar seek performance to RAM, where you can live with fragmentation, but I think the OP's point that there throughput is barely better than a disk is still valid.
You make a good point about bandwidth--that SSDs are more like disks. However, OP doesn't mention bandwidth, nor is it relevant to his experiment.
What would it mean for "SSD to be like slow memory"? To me, it would mean that both bandwidth and seeks would run proportionally slower. This is why I'm using the "characteristic size" metric--to evaluate that proportionality (and to give it a physical interpretation).