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From: Peter on 7 Apr 2008 13:31
Hello,

I want to buy the Abit IL9 Pro motherboard:

http://www.abit.com.tw/page/uk/motherboard/motherboard_detail.php?pMODEL_NAME=IL9+Pro&fMTYPE=LGA775

It has 4 SATA connectors, but does that mean that it also has 4 SATA
busses? It's very important that it has, as I want to run software
raid.

I send an email request to ABIT, but they haven't answered me yet, and
I need to know as soon as possible.


Thanks
/Peter
From: Paul on 7 Apr 2008 16:31
Peter wrote:
> Hello,
>
> I want to buy the Abit IL9 Pro motherboard:
>
> http://www.abit.com.tw/page/uk/motherboard/motherboard_detail.php?pMODEL_NAME=IL9+Pro&fMTYPE=LGA775
>
> It has 4 SATA connectors, but does that mean that it also has 4 SATA
> busses? It's very important that it has, as I want to run software
> raid.
>
> I send an email request to ABIT, but they haven't answered me yet, and
> I need to know as soon as possible.
>
>
> Thanks
> /Peter

The advert mentions an Intel chipset, of 945P/ICH7. You can look them up
and read about them, if you want to. Many other companies don't provide
public datasheets.

http://www.intel.com/design/chipsets/datashts/307013.htm (ICH7 datasheet)

The SATA cables are independent of one another, at the physical level.
They are bridged to the DMI (Northbridge to Southbridge) bus. There is
one SATA controller (D31:F2) for the four disks.

Northbridge (945P)
|
| DMI 1GB/sec (and bidirectional)
|
Southbridge (ICH7)
| | |
| | PCI Express (6 lanes maximum)
| |
IDE SATA
| | | | |
IDE Disk #1 --+ | | | +--- SATA Disk #1
| | | |
IDE Disk #2 --+ | | +----- SATA Disk #2
| |
| +------- SATA Disk #3
|
+--------- SATA Disk $3

Whether they can be operated in RAID, is determined by the OS and
the drivers available. In Windows, the ICH7 would not support RAID
(because Intel provides drivers that are keyed to device enumeration,
and you'd want an ICH7R in order to get Intel to provide a RAID
driver).

There is a trick in Windows, where disks with ordinary connections,
can be run in RAID mode. This was the subject of an article on
Tomshardware, a number of years back.

In Linux, it should not be a problem, because Linux could take ordinary
disk connections and run software RAID over them.

As far as I know, there is nothing in the hardware itself, to support
RAID. The device enumeration differs between ICH7 and ICH7R, and Intel
uses that to enforce what kind of drivers can be loaded. Intel also
charges the motherboard manufacturers a different price for the
two chips. But the chips are otherwise identical.

The enumeration info can be seen here. Check page 21 of 30701423.pdf
for the table of values - that is how the Intel driver can tell what
kind of chip it is connected to.

http://www.intel.com/design/chipsets/specupdt/307014.htm

Paul
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