[CentOS] Boot disk order: h/w vs. grub

MHR mhullrich at gmail.com
Mon Oct 6 05:48:29 UTC 2008

I'm still having conceptual trouble with this one.

I have two PATA and two SATA disks in my home system.  When the system
comes up, these are, espectively, /dev/hda, /dev/hdb, /dev/sda and
/dev/sdb.  I have the boot order of the drives in the boot PROM set to
boot from /dev/sda (hard drive 2), then /dev/hda (hd 0), and usually
that works fine.  /dev/sda is properly set up with the MBR and /boot
lives there as well.

However, when the system has to be shut down, usually for some length
of time more than just a few seconds, when it comes back up, it can't
find the boot image.

I forgot how I got around this the first time.  The second time, when
it wasn't booting past the "GRUB" part of the grub announcement, I
used the installation disk, booted into linux resuce mode, chroot'd to
the actual system disk and re-did grub-install.  Still, a few days
later (last Tuesday) when my video card went south, I just edited the
grub boot line to use root(hd2, 0) and it came up, followed by several
reboots with unmodified grub config lines.

I guess I'm wondering if there's some more permanent way around this
issue.  Do I need to overwrite the MBR on hd0?  Should I reconfigure
the system so the PATA drives are not connected to the m/b at all
(i.e., usb enclosures)?  Is this a bug in grub?  All this is assuming
that I do not get rid of the PATA drives and/or get a new m/b that has
<something else>....

It seems strange that this should be such a pain, even though in a
rather oddball way it makes sense.




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