Promise Pegasus J4 Thunderbolt: Performance with Hard Drives
Hard drives are not as fast as SSDs, but in a 4-way RAID-0 stripe they can deliver high sustained transfer speed.
A RAID-1 mirror is another possibility and has some read-speed benefits as the capacity is filled up.
Performance with 1/2/3/4 SSDs on incompressible data (and RAID-1 mirror).
Tested with diglloydTools DiskTester.