Independence of SATA channels and ports

Question

I'm working on setting up a simple RAID and am wondering about how independent my SATA ports really are. There are 4 ports on the motherboard, but lspci shows only two controllers

00:0e.0 IDE interface: NVIDIA Corporation MCP51 Serial ATA Controller (rev a1) (prog-if 85 [Master SecO PriO])
    Subsystem: Micro-Star International Co., Ltd. Device 7350
    Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 21
    I/O ports at b800 [size=8]
    I/O ports at b480 [size=4]
    I/O ports at b400 [size=8]
    I/O ports at b080 [size=4]
    I/O ports at b000 [size=16]
    Memory at fbffd000 (32-bit, non-prefetchable) [size=4K]
    Capabilities: [44] Power Management version 2
    Capabilities: [b0] MSI: Enable- Count=1/4 Maskable- 64bit+
    Capabilities: [cc] HyperTransport: MSI Mapping Enable- Fixed+
    Kernel driver in use: sata_nv

00:0f.0 IDE interface: NVIDIA Corporation MCP51 Serial ATA Controller (rev a1) (prog-if 85 [Master SecO PriO])
    Subsystem: Micro-Star International Co., Ltd. Device 7350
    Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 20
    I/O ports at ac00 [size=8]
    I/O ports at a880 [size=4]
    I/O ports at a800 [size=8]
    I/O ports at a480 [size=4]
    I/O ports at a400 [size=16]
    Memory at fbffc000 (32-bit, non-prefetchable) [size=4K]
    Capabilities: [44] Power Management version 2
    Capabilities: [b0] MSI: Enable- Count=1/4 Maskable- 64bit+
    Capabilities: [cc] HyperTransport: MSI Mapping Enable- Fixed+
    Kernel driver in use: sata_nv

The kernel log at boot shows

ata1: SATA max UDMA/133 cmd 0xb800 ctl 0xb480 bmdma 0xb000 irq 21
ata2: SATA max UDMA/133 cmd 0xb400 ctl 0xb080 bmdma 0xb008 irq 21
ata3: SATA max UDMA/133 cmd 0xac00 ctl 0xa880 bmdma 0xa400 irq 20
ata4: SATA max UDMA/133 cmd 0xa800 ctl 0xa480 bmdma 0xa408 irq 20

Would this mean I have two channels with two ports each? If so, a RAID 1 with two drives should ideally be set up with each drive on a separate channel (although performance may not really be noticeable)? Or is each port still independent?

Answer 1

Would this mean I have two channels with two ports each?

No. Each regular SATA 'channel' only connects to one drive.

The exception to that would be if you used a port multiplier, but that is quite uncommon in consumer space and depending on the type of multiplier you would need to explicitly configure it. Since you do not mention doing that I am answering "No" to this part of the question.

If so, a RAID 1 with two drives should ideally be set up with each drive on a separate channel (although performance may not really be noticeable)? Or is each port still independent?

For IDE/P-ATA you are right. For SATA this should not matter.

Question: If your BIOS/controller configured for the normal AHCI mode or are you booting in legacy mode? The latter might explain why you are seeing old-style information when you list the PCI configuration.