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Mercury Extreme Pro 3G Single Drive Performance

Last updated April 16, 2010 - Send Feedback

This page discusses single drive sustained transfer rate.

Mac Pro single drive sustained transfer rate

Sustained transfer tests were performed using the DiskTester fill-volume command. For the single-drive test, the SSDs were plugged into the Mac Pro internal SATA drive bays.

For a single drive, write speed hits 257MB/sec and read speed about 270MB/sec. The drop-off at the end is typical of all drives, and related to operating system behavior.

What’s so impressive is that the speed stays high, even on the 2nd pass, and even after I wrote 1/2 million 128K files to a RAID 0 stripe of the two drives, a scenario that will badly internally fragment many SSDs.

Crucial 128GB SSD drive performance graph
MB/sec filling the entire drive capacity
Click for larger image

MacBook Pro 17" 2009 single drive sustained transfer rate,

The 2009 Apple MacBook Pro series has an internal SATA connection which is impaired in some inexplicable way, starting with 2009 unibody models (older models might be affected also). Write performance tends to be sub-par and erratic, and I’ve seen this with more than one brand of SSD, though read performance is high. Because the MacBook Pro stands to gain more than just about anything in terms of performance, this is is disappointing.

The test results shown here used the 2009 Apple MacBook Pro 17" 2.93GHz model. Average speeds for Disktester fill-volume were 179 MB/sec write, and 261 MB/sec read. This is outstanding performance of course, but it’s still a disappointment to see the 257 MB/sec of the same drive in the Mac Pro lose 78 MB/sec, dropping to 179MB/sec in the MacBook (semi?) Pro. As well, performance is not consistent. This is particularly an issue for Photoshop scratch volume performance.

Immediately following this test, I confirmed that the results above with the Mac Pro remained as good as ever, showing that the MacBook Pro SATA port is the culprit, not the SSD itself. I also tested a second copy of the SSD, and found similar results, so it wasn’t one particular unit. Just as the Sonnet E4P shows superior performance to the Firmtek SeriTek card, so too can different SATA interfaces vary in performance. Perhaps a 2010 MacBook Pro will fix this problem.

Crucial 128GB SSD drive performance graph
MB/sec filling the entire drive capacity on 2009 unibody MacBook Pro
Click for larger image

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