Let's say I have a SATA II 4-port IDE controller, a SATA I 4-port PCI IDE controller, an on-board 2-port SATA controller. If I have 4 SATA II disks, do I want to put them all on the SATA II controller, or is it better to spread them across the different controllers? Is the on-board SATA controller free of IDE contention? i.e. Would it be better to put the parity drive on the on-board controller, separate from the other data drives?

 

If I have to I'll do some experiments, but I was hoping someone else with more hardware knowledge than me would already know the right answer.

Based on my limited knowledge of the unRAID architecture, I suspect it doesn't matter which option you choose.  Read operations only use one drive, while write operations only two (data + parity), neither of which should overload a controller.

Thanks for the reply. Is there any risk that writing to two drives will overload the PCI bus? If so does it make sense to put the parity drive on the motherboard? (I think that controller runs straight to the southbridge rather than the PCI bus.)

 

I tried informally putting the parity drive on the MB controller and it didn't seem to make a big difference.

BillK is right: since writes involve only 2 disks, for SATA it won't matter which 2.