AS SSD (incompressible data)
AS SSD uses incompressible data. SSDs with a SandForce controller (like the OCZ Vertex 3, Intel SSD 520, and many others) can therefore not take advantage of the built-in compression tricks.
AS SSD performs both read and write tests. First it tests 4kB data blocks with one command at a time, then it tests 4kB data blocks with 64 simultaneous commands. Lastly, it performs a sequential read and write test, which measures how well the SSD works with very large files. Based on all the tests, AS SSD also gives an aggregate score.
Looking at that total score, the Samsung 840 Pro 256 GB takes the lead with 1,144 points, followed closely by the OCZ Vector 256GB with 1,139 points. The Plextor M5 Pro 256GB, OCZ Vertex 4 256GB, Corsair Neutron GTX 256GB and Corsair Neutron 256GB also score over the 1,000 mark. The Samsung 840 Pro 128 GB is the only 128 GB SSD to score more than 1,000 points.
The AS SSD sequential write test provides the best indication of write performance, since it employs incompressible data. The results vary from 127 MB/s to 491 MB/s. The Samsung 840 Pro 256 GB takes the lead, but the OCZ Vector 256GB, de Corsair Neutron GTX 240GB, OCZ Vertex 4 256 GB and Plextor M5 Pro 256 GB also score better than400 MB/s. In this test you see a clear difference between 128 GB and 256 GB models.
Reading and writing 4k data blocks is done the fastest by the Samsung 840 Pro and 840, Plextor M5 Pro, OCZ Vector, Corsair Neutron and Neutron GTX and the OCZ Vertex 4.
4k blocks read - single threaded
4k blocks read - 64 threads
4k blocks write - single threaded
4k blocks write - 64 threads