system_profiler command details

I don't think I've so much as seen a scsi connector since early in the 1990s. Modern macs use IDE and SATA for internal connections and USB, Firewire or Thunderbolt for externals. If you have an old, old machine (a PowerPC model or earlier) you may have scsi cables somewhere in there, but I think the data type is primarily included for backwards compatibility.

well, IDE would probably be placed under SPParallelATADataType. If you want both, use borh keywords, or try SPStorageDataType. if you enter system_profiler -listDataTypes in terminal it will give you the full list of data types, and you can reason it out from there.

then use both keywords:

system_profiler -detailLevel mini SPSerialATADataType SPParallelATADataType

It would really help to know the model/year of the machine(s) you are working on. if you're running 10.7 the machine must have in intel processor (or xeon from the specs), and your internal disks will be SATA. You may have a PATA internal drive if you've converted the optical bay to a hard drive.

Honestly, you should open the System Profiler application (renamed System Information in later OSes), find the section in the list at left that contains the information you want, and then look through the list of available keywords in terminal to find one that matches. The Bluetooth tab translates to the SPBluetoothDataType, the Ethernet Cards tab translates to the SPEthernetDataType... It's straight-forward.

You might look into the diskutil utility, which can give you all the information system_profiler does in an easier to parse format. or if this is a cocoa app forget about invoking command-line utilities and use NSFileManager.

you probably want to use SPSerialATADataType. SCSI connections are archaic - I don't know that any MBP ever used them - so there is probably nothing to report for that data type.

Have system_profiler output all of the data for your machine and see where it puts the hard disk info. As far as I know, all internal drives are SPSerialATADataType.