[CentOS] grub.conf corrupt in boot grub, fine in rescue shell

Mon Dec 17 07:34:50 UTC 2012
Kenneth Porter <shiva at sewingwitch.com>

--On Friday, December 14, 2012 10:53 PM -0800 "James A. Peltier" 
<jpeltier at sfu.ca> wrote:

> It's quite likely a software RAID card and when the OS was installed it
> only installed grub on one of the hard disks, the one that it thought was
> primary.  I've seen this happen with quite a few software cards.  Each
> time the OS booted it would load a different hard disk as primary.  If
> you can, try disabling RAID on it all together.

Thanks. I completely disabled the Nvidia RAID controller in the BIOS and 
that made the 6 drives appear normal. I then had to delete the RAID 
metadata from the last 4 drives with dd, as there's a bug in dmraid that 
computes the offset to the metadata wrong. (It reports the offset and 
length to the metadata in bytes, then tries to use the same numbers as 
records to clear the data.)