Just to clarify, there's nothing to stop you running SATA and SAS in the same RAID logical drive if it's implemented in software, whether the OS is Windows, Linux, Solaris, AIX, etc - they don't care about the disk hardware type just the size, though it'd be a bit pointless to do so.
A lot of hardware RAID controllers support having 2 logical drives, one made up of SAS drives and one of SATA drives. It's fairly common because a typical server setup might consist of 2 small SAS drives in a RAID1 partition handling the OS, log files, etc, and 4-5 SATA drives in a RAID5 partition handling file serving.