[CentOS] Intel Matrix SATA RAID drivers

[Bryan J. Smith <b.j.smith@ieee.org>]

From: Mickael Maddison <mike at kamloopsbc.com>
> Hello CentOS,
> Does anyone know if there's a driver out there that'll enable CentOS
> 4.x to use the Intel Matrix SATA RAID settings on the 915 chipsets?

All FRAID cards do is setup the RAID organization in the 16-bit Int13h
disk services.  In other words, the vendor introduces its own data
organization for RAID, instead of relying on the OS.

So there's really no such thing as a RAID driver for any FRAID card
(Fake/ Free RAID) implementation.  It's all software RAID.  The system
directly drives the ATA channels, which means the OS uses the standard
ATA driver.

That means that the FRAID card must either:

A)  Provide the FRAID logic as a kernel module

A few do, and it's a massive binary object that is kernel build-specific.
The FRAID logic is licensed from a 3rd party, and that 3rd party makes
all of its money from that proprietary logic, so it will never be GPL.

B)  Write a data organization/interface wrapper kernel module to Linux's
ataraid.c FRAID logic module.

The GPL/reverse engineered hptraid.c, pdcraid.c and silraid.c modules
are examples that don't work well at all, and only for a few models of
each.

C)  Write a data organziation/interface wrapper to Linux's LVM/MD
instead of the ataraid.c logic module.

This is far more ideal and higher performing, but it makes it OS-specific.
I believe this might be what the RAIDCore cards do for Linux support.

Intelligent, hardware RAID don't have to do A-C, because the RAID
logic is on-board in the firmware, driven directly by an on-board
microcontroller or ASIC.  FRAID cards use your host CPU and software.

That's why RAID are so cheap and have *0* additional hardware over
a standard ATA controller.


--
Bryan J. Smith   mailto:b.j.smith at ieee.org