I was looking at a server online and I thought to my self if you could use your typical SATA Hard Disk drive on a SCSI hot swappable HDD server? So basically if one was to acquire a server with SCSI Hot-Plug Hard Drive Bays, could you use say a large SATA drive instead (assuming the mobo can handle it) thanks,

SCSI is not SATA, nor are they compatible. Your question is akin to asking if an old PS/2 keyboard can be plugged into USB.

Exactly what I thought. An adapter will work though to allow one to use the larger cheaper drives correct?

There are adapters to plug SATA drives into SCSI interfaces, but they don't run cheap ($100+), and I don't know how much they retard performance. Also, SCSI is a collection of interfaces, so make sure you get the adapter compatible with your server.