alt Hacker NewsSSD still have slower reads when the data isn't sequential. Not slow enough to matter, especially with extents meaning the data is probably in a handful of locations, not 10000, but it's absolutely measurable if your blocks are small enough (<1MB typically, though disk benchmarks usually use 64KB random reads and sometimes 4KB).
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Joel_Mckay • today at 4:18 AM
Except most SSD also don't store pages sequentially internally (hidden flash wear leveling is even in microsd cards now), and the dram/SLC buffer areas are finite especially on low end budget hardware. Don't defrag your SSD dude. =3
It's more complex than that... Sequential reads are faster than random reads across most mediums (including system ram), but if there's enough prefetching, you might get better throughput on an SSD with the data fragmented than contiguous because SSDs can often read from multiple regions in parallel and contiguous data might not allow for that.
If you're at the point where you're optimizing for this, you've got some really high performance requirements though. And you'll have to do your own testing, because rules of thumb won't do.