ks pre script to determine hw raid drive to install to

[Bryan J Smith]

On Thu, 2009-02-12 at 13:42 -0500, Rodney Mercer wrote:
> I just purchased a Sun Fire X2250 rack mounted server to use as a build
> machine. I have set it up to use the built in hardware raid to mirror
> the two 250 GB disks. I am using RHEL 5 update2 X86_64 ...
> This setup works great on the non hardware raid machines. With the
> raided Sun Fire X2250, it fails to determine the device name of the
> raided Volume but sees the individual disks, /dev/sda and /dev/sdb.

That's not hardware RAID.  That's Fake [Hardware] RAID (FRAID).  The
RAID is done 100% in software.  The only "additive" is that there is a
"trick" in the 16-bit BIOS so the functions write to the organization.

Once the OS starts, it sees the "real" drives and nothing more.  So a
"trick" must be done on the OS side as well.  In either case, whether
the 16-bit BIOS or 32/64-bit OS software, it's 100% software RAID.

Under Windows, this is some 3rd party licensed logic.  It's very
proprietary and non-portable.  Many times, I've seen it break and ruin
different volumes.

> Of course it fails the partition. Commenting out the part directives
> shows me that raided volume name
> is /dev/mapper/isw_dficaggeej_Volume0.

Under Linux, that's Device Mapper RAID (dmraid) mapping the /dev/sda
and /dev/sdb drives as /dev/mapper/isw_dficaggeej.  DeviceMapper can
read a number of the FRAID disk organizations and figure out how to map
appropriately for striping, mirroring, parity, etc..., leveraging more
generic RAID code in the Linux kernel.

It's actually much safer than the Windows driver.

The big problem though is rebuilding after a failure.  The tools don't
seem to be there for dmraid the last time I checked.

> If I hardcode "d1=isw_dficaggeej_Volume0" and restore the part
> directives, the install completes without a problem.

Correct.  Because you are now installing to the device mapping setup for
the FRAID volume.

> Does anyone know how to have the pre script recognize the hardware
> mirrored device volume name and use it automatically?

I haven't seen a problem with Anaconda since Fedora Core 5/6 or so and
Red Hat Enterprise Linux/CentOS 5.  What is the Intel ICH, nVidia MCP,
etc... chipset here?

If you don't know, use "lspci"


-- 
Bryan J Smith - Senior Consultant - Red Hat GPS SE US
mailto:bjs at redhat.com      +1 (407) 489-7013 (Mobile) 
mailto:b.j.smith at ieee.org  (non-RH/ext to Blackberry) 
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