[BC] RAID servers

[RichardBJohnson at comcast.net]

There is a problem with some RAID controllers in that
they require some software to be loaded into them (FPGA code)
during the boot process. This usually happens when a driver
is installed. The driver has a bucket full of bits that it
uploads during its initialization. The problem exists that
the RAID array is damn dumb until those bits are loaded.

This means that the first disk in the array looks like something
bootable to the BIOS, but none of the other drives are even
known to exist. If the RAID array is supposed to support
booting, then it needs to be built (using software) so
that it can handle the boot process.

Under Linux, any such RAID array is initialized so that the
first disk in the array contains the boot partition plus any
striping for the rest of the array. This is fine unless you
lose that first disk. If it’s lost, you can’t boot normally.

However, Linux has a work-around where you boot the installation
DVD. This loads the drivers. Then, you can execute a shell and
rebuild the array as well as repartition a new boot disk after
which you reinstall the boot loader (grub).

Better RAID devices load their own FPGA code when they are reset.
The FPGA code is in a serial EEPROM that costs about a dollar.
Other companies that make RAID controllers are so cost conscious
(read cheap) that they cause all kinds of problems to save that dollar.

Cheers,
Richard B. Johnson
Book: http://www.AbominableFirebug.com/

----- Original Message -----
From: "Bernie Courtney" <bcourtney at metrobcast.com>

That is incorrect.  If you have a proper raid controller in the machine, the
OS see's a virtual drive and can install to that.  If you loose a drive, you
go into the BIOS on the controller and rebuild the array no sweat - that's
the whole point of a true RAID array.  Some of the cheap 'RAID' solutions
marketed are not really true RAID controllers  that support bootable OS's
residing on their drives.