In the BIOS I can't find any distinction in how the drives are labeled other than 3M/3S/4M/4S/PM/PS. How do I figure out which physical SATA ports these labels correspond to on the motherboard?
I'm assuming your motherboard's drive controller is in IDE mode.
First let's understand the M and S in the labels. IDE (sometimes referred to as ATA or PATA) hard drive controllers use the concept of Master and Slave ports, so:
M = Master
S = Slave
One Master and Slave port form a single IDE channel as shown here, where the blue connector is the Master port and the black one is the Slave:
Therefore your BIOS labels correspond to IDE channels and Master/Slave designations:
3M = IDE Channel 3, Master
3S = IDE Channel 3, Slave
But why does your BIOS start with Channel 3?
For legacy purposes your BIOS manufacturer skips (reserves) IDE channels
2 because some motherboard designs could physically include the corresponding IDE ports, in which case they would be designated as follows:
Physical port 1 = IDE Channel 1, Master
Physical port 2 = IDE Channel 1, Slave
Physical port 3 = IDE Channel 2, Master
Physical port 4 = IDE Channel 2, Slave
We could shorten this up to
1M/1S/2M/2S. Clearly your port labels continue on with
3M/3S/4M/4S simply picking up where the reserved ports end.
What about the
P in the labels
It appears your motherboard treats physical SATA ports 5 and 6 differently (see page 3-13 of the manual), designating this Master/Slave pair as a
Primary channel (instead of channel 5). Two reasons for this come to mind:
- During its heyday, IDE designs never had more than four channels
- IDE was often referred to having a Primary and Secondary controller
The Primary and Secondary controllers typically consisted of one channel each, where the Primary controller was included on the motherboard and, if present, the Secondary controller would be on an add-in sound card. Later, both controllers were included on motherboards. According to Wikipedia:
This second ATA interface on the sound card eventually evolved into the second motherboard ATA interface which was long included as a standard component in all PCs. [These are] called the "primary" and "secondary" ATA interfaces...
So apparently your BIOS manufacturer didn't want to designate the last channel as
5 and decided to call it (somewhat confusingly) a
Bringing all of this together, your labels
3M/3S/4M/4S/PM/PS correspond to your physical SATA ports as follows:
Physical Port SATA Port IDE Labels IDE Full Name
1 1 3M Channel 3, Master
2 2 3S Channel 3, Slave
3 3 4M Channel 4, Master
4 4 4S Channel 4, Slave
5 5 PM Primary channel, Master
6 6 PS Primary channel, Slave
That all said, none of this will help you determine which of your six identical drives is the boot/OS drive. The only way you'll be able to do that is connect the drives one-by-one (preferably to physical SATA Port 1) and attempt to boot the computer. If that fails, then you'll need to use another computer to examine the content of the drives in order to determine which one has the OS on it.