HighPoint RocketRAID 4522 8-Port External SAS 6Gb/s PCIe 2.0 x8 Hardware RAID HBA (SAS Tape / RAID Support)

I'm using this in a 2008 Mac Pro to drive a 4TB RAID 5 made from 4 1TB WD Constellation ES SAS drives connected to a single port on the card. I consistently get >330MB/sec read and >380MB/sec write from the single channel. I expect that would improve on a dual channel RAID setup.The only complaint I have is that the alarm on the card is *very* loud, and you have to boot the computer and go to the local web admin page to turn it off. (This was discovered when very old SAS disk on the second channel failed.)

It might have been just the unit that I got, but after a few weeks I had to return it. My Mac Pro was very unstable almost to the point of becoming unusable.