Comparing SSD benchmarks

Question

here's the problem...

I am looking at some SSDs benchmarks, but when comparing I didn't understand some benchmarks on tom's hardware and on passmark. Why is the Vertex 4 behind the other two drives but has more iops and w/r speed?

Su passmark (HDD benchmarks):

SSD OCZ Vertex 4 128GB 2.5"      2,666
SSD Corsair Force GT 120GB 2.5"  2,869
SSD OCZ Vertex 3 120GB 2.5"      2,798

IOPS

SSD OCZ Vertex 4 128GB 2.5"      R4kW 85000  M 120000
SSD Corsair Force GT 120GB 2.5"  R4kW     ?  M  85000
SSD OCZ Vertex 3 120GB 2.5"      R4kW 60000  M  85000

Can somebody explain how those differences come up?

Answer 1

Since Passmark are not very open about what kind of transfers give the most points, I'm unable to tell you why the Corsair Force GT scores higher than the Vertex 4. What I can tell you, is that there's multiple ways to measure drives' performance:

1. Sequentiel Read/Write (how quickly a drive can read/write a huge file, in sequence)
2. IOPS - Input/output per second. How quickly a drive can transfer multiple files. Changes dramatically by size, which is why you test for 512b, 1k, 2k, 4k, 8k etc. R/W. For OS-style operation of the ordinary user, 4k reads matter the most. Source.

And suites like Passmark, which assign a certain value to each performance measurement, adding them together to give a "score" for each drive. Unfortunately these scores can be misleading, as what Passmark value as important, does not necessarily fit your usage scenario.

While not a perfect answer to your question, it might be the beginning of an explanation.