Its very risky to use disks that large in a raid 5. Ideally, those should be setup in a raid 6.

I have raid 5 setup on a dell 2970 running server 2008. Drive performance has been terrible, so i suspected 1 of the drives was kicked out of the array.

Learn the characteristics of RAID 10 and RAID 50, and which RAID level is appropriate for your app. I/O and protection needs contribute to your RAID choice.

One of the major changes was that Apple removed any ability to set up and configure a redundant array of independent disks (RAID). You had to turn to a third-party app to do so.