SATAI = 1.5Gb/s
SATAII = 3.0Gb/s
SATAIII = 6.0Gb/s
A single HDD can't get to 150MB/s sustained yet. SSD's can saturate their respective links.
As stated above.
An ssd can saturate a SATA2 connection and below easily as Sata2 is 3Gbps which is roughly 375MB/s. No single mechanical drive can saturate a single bus right now, nor can I see that changing in the near future.
And also adding a Sandforce SATAIII SSD can saturate a 6.0Gb single bus. 560MB/s is pretty close to full saturation forgiving any overhead.
I am going to disagree on that one , since sata 3 is 6Gbps which is about 750MB/s, and from reading, the overhead is about 10% at worse so 7MB/s