[CentOS] Changing boot drives

Wed Aug 13 01:22:55 UTC 2008
MHR <mhullrich at gmail.com>

This is probably a dumb question, but I haven't found anything that
clearly describes what I need.

My system has 2 IDE (PATA) hard drives and 2 SATA hard drives.
/dev/hda is the boot drive, but /dev/sda contains my CentOS
installation, including /boot, /, /home and swap.  I know for a fact
that there is no MBR on /dev/sda because the system refuses to boot
from it.  I would like to rearrange the boot order to use /dev/sda as
the boot device (mainly because I'm probably going to get either
another disk drive or both another disk drive and a m/b soon that does
not have two IDE connectors (I have two IDE DVD burners) and I'd
rather not replace any more than absolutely necessary to accomplish

So, what is the best way to put a correct MBR that will boot from
/dev/sda on /dev/sda if /dev/sda is the first boot device?