Why does the BIOS have Master/Slave for SATA drives?

[alokep]

This is  on a GA-X58A-UD5Rev 2 board with X58A-UD5 FE Bios with AHCI enabled.

The drive has room for 10 SATA drives, as seen in the motherboard layout (From the manual pg 7).
SATA2_0 .. SATA2_5 are on Intel Southbridge, GSATA3_6, GSATA3_7 are on Marvell 9128, and GSATA2_8, GSATA2_9 are on Gigabyte SATA controllers.

Each STA port can handle one SATA HDD.

Why does the BIOS settings for the drives have separate settings for Master and Slave for each channel?  See attached files.

Thanks.
Aloke

[absic]

Hi there,

this is nothing to worry about although it is more than a little confusing. It is down to the way the BIOS is written and is a hangover from the way IDE drives were identified and handled.

[alokep]

Thanks.

There are so many questions about that page:

Why do Channels 2, 3 and 7 have Master only?

Why is Channel 8 missing altogether?

Am I correct that these "Channel 0 ..9" on that BIOS page refer to the 10 SATA drives I listed in my OP?

Thanks again.
Aloke