[CentOS] SATA RAID on CentOS!

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

From: israel.garcia at cimex.com.cu
> I want to install CentOS 4.0 on  my new server (two SATA hdds, Intel 865
> mainboard), now, I want to configure a RAID 1 using this hardware..., my
> question is:
> 1. Setting up a RAID 1 on SATA hdds is different from a normal hdds
> (PATA)?

SATA channels are designed to be legacy compatible with software for
legacy ATA channels, _unless_ you put them in Advanced Host Controller
Interface mode.  In AHCI, instead of individual I/O ports, the system
presents a single device of up to 32 devices, along with some capabilities
for each drive (e.g., native command queuing, NCQ).

In legacy ATA mode, each drive is assigned a device.
AHCI support varies in Linux right now (i.e., don't use yet!).

True Hardware ATA RAID controllers provide queuing natively, since
they are queuing with an on-board intelligence (microcontroller or ASIC),
and not just a "dumb" interface to the drive.  In essence, the "intelligence"
moves from the driver to the on-board firmware, and the OS driver becomes
"dumb" (and GPL as a result ;-).

> 2. Is there some SATA RAID Linux Howto available?

The same HOWTOs/documentation for LVM/MD applies regardless of
ATA, SATA or SCSI when using software LVM and/or MD.





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