Recently I had a problem with one of my IDE drives.../dev/hda1. So I decided to replace it with a nice new sata drive. I am not using raid. I installed the drive....booted up and it was recognized by the BIOS as the 2nd drive. Grub pops up and I select my kernel and grub can't find it. Here is what I see (running Gentoo)

root (hd4,0)
Filesystem type is reiserfs, partition type 0xa5
kernel /boot/newkren root=/dev/sda3

Error 15: File not found

Press any key to continue

For further clarity:

/dev/sda1 = /boot
/dev/sda2 = swap
/dev/sda3 = /

grub-install has confirmed that sda is hd4...boot partition of course being hd40.

At any rate, I got out my Gentoo install CD...booted off it and noticed Linux does see all my partitions and everything looks good. So I mount /dev/sda1 to /mnt/Getnoo/boot and go over and look at my kernel newkern sitting right there in /boot. Everything worked fine prior to me installing the new SATA drive. Any ideas?

I think I see the problem.

You have /boot in it's own partition, seperate from / (the root of the filesystem).

Your grub config doesn't tell grub where to find the rest of itself in /dev/sda1. Root is now in /dev/sda3 (hd4,2 in grub speak).

root (hd4,0)
Filesystem type is reiserfs, partition type 0xa5
kernel /boot/newkren root=/dev/sda3

Try editing the config so that it looks like this:

root (hd4,2)
Filesystem type is reiserfs, partition type 0xa5
kernel (hd4,0)/boot/newkren root=/dev/sda3

The addition of the /boot partition location in the kernel line is how it's shown in a SUSE installation. It may work in Gentoo as well.

Thank you for your help. I now get:

root (hd4,2)

Error 22: No such partition.


As a further point of clarification, this is not a new install. This grub config worked prior to me adding a new disk that currently has not been partitioned or even a file system built on it.Completely in the raw. I totally don't understand why this would cause grub not to boot.

IMO grub uses a file called device.map (/boot/grub/device.map) that looks similar in your case to the following:
It is used due to the fact that grub sometimes has problems guessing devices from the BIOS. When you removed the IDE drive the mapping changed and grub is now looking in the wrong place. Removing the old IDE device and reordering the devices should get you back in business.

This should also rebuild the device.map file
delete the old device.map file and invoke grub like:
grub --device-map=/boot/grub/device.map

Thank you. I do appreciate all your help. I cheated. I simply:

emerge --unmerge grub
emerge lilo

Back in business. Always was fond of lilo anyway.

That however is not to say this is all for not. Just out of curiosity, you mention grub is now looking in the wrong place. When you say that though, since we are speaking of the act of booting up the kernel, I almost wondered if for a moment you thought my kernel was on /dev/hda? My kernel was actually on /dev/sda1. I did remove /dev/hda though. I just wanted to clarify because this would be good to know going forward on other machines I have running grub still. If grub will fail to work on the removal of any drive, regardless of if it has a kernel on it or not...due to changes in the device map, that is good information.