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Mercury Accelsior PCIe SSD — Performance Singly and Striped
Related: camera cards, Mac Pro, Other World Computing, OWC Extreme Pro 6G, PCIe SSD, RAID, SDXC camera storage card, SSD, storage
The OWC Mercury Accelsior offers a very high level of performance far exceeding that possible with a conventional SATA-based SSD.
OWC provided MacPerformanceGuide.com with two 240GB and two 480GB OWC Mercury Accelsior cards on loan for testing.
Technical note: The Accelsior cards tested were configured onboard for hardware RAID-0 striping (the default), a fact which is invisible to the operating system; the 240GB model is actually 2 X 120GB configured internally (on the card) as a 240GB striped pair (can alternately be configured as a 120GB RAID-1 mirror). See the image and note the two SSD modules on the card.
General performance notes
Bottom line is that the Accelsior provides stomping-fast performance for virtually any task. Notes here are nuances that will not be noticed by most users for any real-world task.
Worst and best case: in the real world, most performance will be the best case, the speed seen for 'zeroes'. The absolute worst case it to put the drive under duress, by forcing it to store a completely random data stream (incompressible) for the entire capacity of the drive. A full-capacity incompressible data stream is an unrealistic case for every day use, but shows the absolute worst case, a sort of abusive test of the drive’s mettle.
Other notes:
- Every Sandforce-based SSD slows down for writes of incompressible data (JPEG, compressed TIF, video, etc). Reads are all but unaffected.
- The 480GB model offers higher write performance with incompressible data, as compared to the 240GB model.
- OWC states that on a PC, performance is faster than on a Mac Pro running Mac OS X. An optional driver (not yet available) might improve Mac OS X performance.
- The Apple Mac Pro as of April 2012 has SATA II ports, so the speed of the OWC Mercury Extreme Pro 6G SSD is limited to 300MB/sec by the ports.
Single-card speed
Results shown below are after “seasoning” — several read/write cycles to full capacity with both zeroes and incompressible data.
These graphs compare a single Accelsior card to the OWC Mercury Extreme Pro 6G (on the 2010 Mac Pro SATA II port, the SATA port is limited to 300MB/sec).
- The Accelsior cards trounce the SATA-based SSD.
- The 480GB Accelsior shows superior performance to the 240GB model when writing incompressible data.
The graph below shows the performance of each drive by the type of read or write.
Same data below, but broken out per drive for each type of I/O.
RAID-0 stripe speed
Results shown below are after “seasoning” — several read/write cycles to full capacity with both zeroes and incompressible data.
The 480GB Accelsior shows much superior performance when writing incompressible data.
Graph below shows by the type of read or write for each model.
Same data below, but broken out per model for each type of I/O.
