Sustained Transfer Speed — 2010 Mac Pro Internal 3G Port 120GB Model

The 2011 Mac Pro 3.33 GHz 6-core has 3 Gb SATA II ports— half the speed. So we can expect the SSD to max-out at about 270MB/sec. But that’s not all— a 6G drive run on a 3G port could in fact run more slowly than a 3G drive as it runs in compatibility mode.

Results (zeroes)

The average speeds are slightly slower than the OWC 3G SSD, but not by much. All the drives do show a drop in the last few percent of capacity; this could have something to do with the Mac OS X file system, and I’d suggest ignoring it.

Average write MB/sec: 249.3
Average read MB/sec: 263.6

On both machines, filling the drive beyond 98% of capacity incurs some write speed slowdown; this is a Mac OS X file system inefficiency, not a drive issue.

A fill-volume test using DiskTester was used to gauge the speed across the drive capacity for writes and reads.

Write and read speeds across entire capacity of OWC Mercury Extreme Pro 6G SSD
(Disktester fill-volume test on 2010 Mac Pro internal SATA ports)

Results with incompressible data

The Sandforce controller used in the OWC Mercury Pro series (and all brands using the Sandforce controller) use compression to decrease the wear on the flash memory. This exerts a performance penalty for incompressible data, which includes most digital camera image files, JPEGs, video, sound files, etc.

Read speed is not affected, but write speed is cut in half when purely incompressible data is written.

Average write MB/sec: 126.9
Average read MB/sec: 265.9

Write and read speeds across entire capacity of OWC Mercury Extreme Pro 6G SSD
(Disktester fill-volume test on 2010 Mac Pro internal SATA ports, incompressible data)