If you are setting up an UnRAID system, and are looking to increase the number of SATA ports you have in your system, avoid purchasing/using inexpensive PCI Express SATA Cards. These no-name cards on eBay or elsewhere have anywhere from 2 ports to 8, for $10-20.

The problem with these cheap cards is that they multiplex ports, which is normally okay, and will work perfectly fine for other purposes, but with UnRAID, when you are doing a parity check or rebuild, you are actively using all disks at the same time, which will stress any multiplex configuration, causing resource contention, and eventually timeouts. UnRAID will kick/fail disks that exibit these symptoms.