Bizare problem booting from (some) live CD's

[Diss]

Hi all

I am having problems booting from some live live CD's - history is as follows:

Ubuntu breezy Live CD works fine
i think i then installed a new hard drive
Live CD no longer worked
however Knoppix 4.02 live CD did boot fine
Dapper live CD does NOT boot
Knoppix 5.0 live CD does not boot (it boots ok on my other PC)
but Knoppix 4.02 live CD still boots ok

whats going on here?

What i think may be the problem is as follows (though who knows!)

I think it was after i installed an extra hard drive that i had big problems everytime there wa a kernal update inthat my /boot/grub/menu.lst file would get updated to boot from sda whereas my boot drive is sdb - so i always have to remember to manually edit the file before i reboot - a bit of a pain if you forget!!!

I am thinking that some live CD's try to boot from sda only and others will keep looking until they find a real boot drive????

Is there anyway to make linux think that the sdb drive that it curently boots from is sda?

OR

Do you have any other ideas about what may be going on here?

Many thanks
Diss

 

[Berserker]

Is there anyway to make linux think that the sdb drive that it curently boots from is sda?

Swap drive cables/use the other port/check BIOS settings?

Live CDs shouldn't care what disk you normally use to boot Linux from (or even if you have a disk at all). If you have a configuration issue with the disks you do have (which seems at least plausible in your case), then they probably will care about that.

 

[leezer3]

IIRC you should be able to use the map command to change drive assignments-

map (hd1) (hd0)

That entered in the Grub boot command list should map hd1 to hd0- Alter as appropriate.

-Leezer-

 

[Diss]

thanks leezer - will give it a try but can you be a bit more specific as to what i do - you don't seem to be saying do it in a terminal - how do i get to a grub boot command line? Can i somehow interupt the boot process??

and when i have done that i assume i will need to edit menu.lst back to sda??


however Berserker raised a good point aboutn why it would make any difference for live CD's - so i don't really understand why things go wrong

many thanks

Diss

 

[Diss]

thinking about what you said could i just edit my menu.lst file which looks like this?

title Ubuntu, kernel 2.6.15-26-k7
root (hd0,1)
kernel /vmlinuz-2.6.15-26-k7 root=/dev/sdb4 ro quiet splash
initrd /initrd.img-2.6.15-26-k7
savedefault
boot

winxp is hd 0,0

but to what?


thanks

Diss

 

[leezer3]

Have you got a prompt asking you what OS? This is the GRUB menu- From there highlight the entry that needs the HDD mapping & press E to edit it. It should be relatively self-explanatory from there, just remember that the HDD map command should come before anything referring to the HDD.

Anyway, it shouldn't matter which drive Linux boots off Try changing the hd0,1 in your menu.lst to hd1,1 & see what happens- This ought to be sdb. (I assume you know how to recover from a broken menu.lst?)

If these are IDE drives, you might want to check the master/ slave settings as something extremely odd is going on here. Added to that I'm still a little confused as to what you want to do and

-Leezer-

 

[Diss]

thanks leezer3

the grub boot menu doesn't list drives, just linux kernals and winXP and if i select one of them it just boots to the normal GUI not a command prompt - i assume you can get to a prompt but i don't know how

i'll try changing the menu'lst file as suggested - i can recover if it messes up but only by using an old knoppix LiveCD - presumably theres a quicker way via a grub command prompt as mentioned above - but i don't know how to get that

the drives are SATA - what i want to do is make it so that my memu.lst file gets updated correctly when there is a kernal update as it always chmges sdb back to sda which means the system won't boot at all

thanks
again for all the help

Diss

 

[Diss]

Anyway, it shouldn't matter which drive Linux boots off Try changing the hd0,1 in your menu.lst to hd1,1 & see what happens- This ought to be sdb. (I assume you know how to recover from a broken menu.lst?)-Leezer-

Hi
Sorry its taken so long to check this out. I have tried:
hd1,1 with sdb
and
hd1,1 with sda

but neither would boot at all (couldn't find root partition i think it said

was this doing the same as using your mapping copmmand?

any other suggestions?

many thanks

Diss