[linux-lvm] won't dual boot: 2 disks and LVM

cs cs at networkingnewsletter.org.uk
Wed Dec 19 09:59:28 UTC 2007

On Tue, 2007-12-18 at 16:52 -0500, pham_cuong at emc.com wrote:
> There is a difference between changing the boot order from the BIOS vs.
> [physically] removing the master HD.  Here's why:
> In the former case, the BIOS boot order is at the lower-level (earlier)
> and it will take effect before the boot loader exists in each drive.
> Depending on your BIOS, the boot order can be fixed or priority-based
> (most BIOSes support priority-based boot path).  Fixed order means that
> only the specified boot order is used.  Priority-based boot order means
> that the system will attempt the first boot path on the list, if failed,
> or timed out, goes to the 2nd boot path.  BIOS boot order only changes
> the order of which path to boot from first. It has no control over the
> designation of which drive is detected and designated as drive 0 or
> drive 1.  Boot.ini has this level of granularity, and more... Down to
> the partition level (one below the disk level).
> The act of removing the Master HD changes the HD designation at the
> hardware level, and this in turn may affect how the system boots (for
> non-SCSI only). Specifically, for your case the XP's boot.ini may
> designate that XP is to be booted from the first disk (connected to
> PR1), first paritition, and you've physically connect this drive as a
> secondary/slave (SL) drive so XP will never boot when XP's boot loader
> reads the boot.ini.  Upon either moving this drive to the primary (PR1)
> connection, or change the boot.ini, the drive order for this drive is
> changed from disk1 to disk0, so XP would see this drive and be able to
> boot from it.  As you can see, in this case, changing the BIOS boot
> order is inconsequential.
> Regards,
> Confucius

useful stuff but I'm still unsure why if I change the order in BIOS then
(when I had it working a bit) it would start the XP boot sequence (and
not the GRUB from master) but then hang indefinitely...

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