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Summary So Far of Apple Fusion Technology — Attempted on MacMini, Mac Pro

Apple Fusion technology = a combination of an SSD and a hard drive into a single desktop volume in which the system migrates frequently used files to the SSD to enhance performance.

Apple offers the Fusion drive with the new Mac Mini and the new iMac (which ships in December). The speculation has been that the Fusion technology might work with non-Apple drives.

Note that I have not tested an official Apple “Fusion” setup. My goal has been to see if a 3rd-party SSD plus Apple HDD can work.

What I’ve found so far:

  • Using an OWC 240GB 6G SSD + 1TB hard drive in MacMini, no Fusion “migration” occurs. In short, the Fusion technology does not work with a 3rd party SSD, operating instead as “dumb” JBOD. Apparent reports to the contrary leave me skeptical, or that the model/brand of SSD might matter.
  • The “special” version of Disk Utility is indeed a new build (444), complete with a bug that is eager to merge two separate internal drives/volumes in a Mac Mini. To erase or verify or repair internal drives, one will have to obtain a non-special version of Disk Utility (build 430), or use the command line 'diskutil' until this bug is fixed.
  • On a Mac Pro running OS X 10.8.2 with either a PCIe SSD or SATA SSD, the Fusion technology does not work, operating as “dumb” JBOD.

Other claims based on 'dd'

My testing shows that using 'dd' is a totally inappropriate way to measure disk I/O speed— Disktester reads the same file ~19 times faster than 'dd' (from the SSD or cache, about ~3.8X faster from the HDD).

MPGmini:test admin$ dd if=blob-0999.blob  bs=65536
4096+0 records in
4096+0 records out
268435456 bytes transferred in 9.582504 secs (28013080 bytes/sec)
= 26.7 MB/sec

MPGmini:test admin$ disktester read-files blob-0999.blob
DiskTester 2.2 64-bit, diglloydTools 2.2 fc5, 2012-10-28 13:40
...
Read 1 files totaling 256MB in 0.5 seconds @ 511MB/sec

Furthermore, 'dd' uses the OS X unified buffer cache, so it doesn’t measure disk speed at all if the data is cached.

Hence I dismiss the jollyjinx.tumblr.com 'Fusion' claims in their entirety as unreliable, and an apparent failure in test methodology.


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