[plug] Bios hard drive addressing mode frustration

[Adam Davin]

Good Morning All, 

I performed a hard drive upgrade the other day on a machine with debian installed,(replaced a ~2gb hd with a new 80gb hd) following the "hard drive upgrade howto". I have done this before on other machines and it has worked flawlessly. 

I probably should mention that I have also done a machine upgrade at the same time (moved the old hard drive to the new machine first and then performed the procedures on the new machine.)

I installed the new hard drive, booted the machine off the original hard drive, partitioned and marked the /boot partition bootable, then formatted, mounted the drive and copied the file structure across. Lastly, I edited the lilo.conf under the new partition (/mnt/newdisk/etc/lilo.conf) and then ran "/sbin/lilo -C /mnt/newdisk/etc/lilo.conf". 

When the machine rebooted (after removing the old drive and placing the new drive on the primary master) I was faced with the typical bios message "insert system disk boot failed". I had made a floppy boot disk as well and putting this in, the system booted fine. Once the system came back up I adjusted lilo back to settings applicable for the first drive and tried rebooting again. Same problem "boot failed". Again with the floppy disk installed I got the system to boot. 

In desperation I reconnected the old hard drive and tried doing the partition / copy again and this ended up with the same result (surprise surprise) I tried installing grub and this also came up "boot failed".

I eventually sat back in frustration looking at the insert system disk message and glanced up past the irq allocations to the rectangular box containing summary information. Next to the new hard drive I saw:
	Pri. Master Disk: CHS, 80GB

Something somewhere had mentioned that the drive needs to be using LBA to access the drive. I went into the bios and changed the setting from AUTO to LBA and rebooted, removed the floppy disk and lo and behold, there was life. The system booted and hasn't had any problems since. 

My question then, is what caused the bios to select "CHS" addressing over "LBA"? This is a new MSI 661fm main board and the first machine I have seen default to CHS mode for a drive. Is one mode better than the other?. I was under the impression that CHS was an older addressing mode.

Any thoughts greatly appreciated. 

Regards,

Adam.