On Tuesday 05 February 2008, William Case wrote: > My question is not about the history of the various chips etc., but is > about why do I get three different designations on my computer and how > do I disentangle the information being given me so that I know what is > what? This is somewhat of a different question, then. To tackle things in order: 1.) The nVidia MCP is not a SCSI controller. Yes, I know the linux kernel's libata driver stack treats it like a SCSI controller, but it is not one, it's just emulated. The same is true of USB drives; they are treated like SCSI drives. Alan Cox can chime in with the reasons why this was done. 2.) The seeming discrepancies you are seeing are results of the IDE-SCSI 'merge' in the libata software stack that makes IDE/ATA devices look like SCSI devices to the kernel. So, you get entries in /sys/bus/scsi/devices/ that seem to conflict with /dev/disk/by-id; in fact, the 'ata' you see is telling you that the drives are IDE/ATA drives, not SCSI drives. The kernel, thanks to the libata driver stack, displays them in the SCSI tables since, for all intents and purposes that the kernel cares about, libata exposes the drives as emulated SCSI drives, even they they are not SCSI, but IDE/ATA. Yes, I know it is a tad confusing. You can find more information on the libata pages at http://linux-ata.org/ (even though that page is mostly about SATA, the information applies to the parallel 40-pin PATA IDE drives too, at least in Fedora 8). -- Lamar Owen www.pari.edu
