After much head scratching and buying 2 different 1TB SATA Hard drives, I solved the problem of a dead Xserve drive. My server reported that the drive in Bay 2 was unresponsive and my Apple hardware RAID was in degraded mode. The original configuration used 3 Western Digital drives.
So I had a 1TB Seagate SATA drive, and put it into the drive chassis and slid it in. No luck! Disk Utility couldn’t see the drive. Worried that the server would fail, I plugged the Seagate drive into a USB port and started to clone the system drive. I then order a new Western Digital Black drive with similar specs to the original drives. A couple of days later the drive arrived and still no luck. (I even used an older sled from another server.)
Then I found the answer, the speed of the SATA interface in the Xserve is designed for SATA-150. I grabbed a jumper from an old drive, after checking the WD site for the jumper configuration. I popped the drive into the server. Initially it the drive didn’t show up. So I gave up, rebooted the server and walked away.
A while later, I checked again and the RAID Utility could see the drive running at the slower speed. So I marked it as a “Spare” and the RAID started to rebuild.