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Mercury Accelsior PCIe SSD — Speed vs Capacity and Data Type (240GB)
The results shown below are for the 240GB OWC Mercury Accelsior, which has 2 X 120GB SSD modules installed on the PCIe card. Performance might be even higher with the 480GB model.
See the graph below.
The performance is outstanding.
With a single Accelsior, reads are at 650 MB/sec for both compressible and incompressible data.
Write speed is similar to read speed for compressible data, but for incompressible data, the speed does drop (the absolute worst case of filling the entire drive with incompressible data, continually).
The graph captures an interesting initial-use hiccup in the write speed of incompressible data at about the 600 offset (orange line). Note that a “seasoned” drive offers consistent performance across the drive (gray line).
Since I have observed this behavior with the 120GB Mercury Extreme Pro 6G drives, I believe it to be a general characteristic of the Sandforce controller. The same behavior is also seen with the 480GB Accelsior.
The little glitch at the very end of the test occurs with all types of drives, SSDs or hard drives, and should be ignored.
Click for a larger graph.
With a striped pair (cards tested after the single-card tests and were thus “seasoned”), consistent speed is seen for both compressible and incompressible data across the entire drive.