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GRUB preventing booting from external usb cd rom drive on fedora core 5.

Posted on 2006-06-24
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Last Modified: 2013-12-15
Hello
I have Fedora Core 5 running on my laptop.
Normally, this laptop can boot from usb cd or dvd drives as it doesn't have an internal drive
I installed the FC on the laptop through an external drive.
Through the BIOS screen, it's set up so that it would try booting up the CD drive first.
However, whenever I try to boot up from the CD drive now, the grub loader kicks in and boots the laptop off the hdd and loads fedora core.
This is a BackTrack CD used for security audits etc.
I know the CD is indeed bootable because I can boot my windows xp system with this cd so I know that it works.
how can I make my laptop boot off the external cd drive?
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Question by:eggster34
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17 Comments
 
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Expert Comment

by:xberry
ID: 16982194
Have you tried a different bootable CD ?

Also, it would be interesting to try following thing:
In your Bios, disable all your boot entries, except that one for the CD-ROM drive.
Can you boot the CD then ?

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Expert Comment

by:rindi
ID: 16985496
Temporarily disconnect the HD from the system.
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Author Comment

by:eggster34
ID: 16986626
This cd boots on other systems
and other cds that boot on other systems do not boot on this one.
I cannot disable the hdd on my bios, and I cannot disconnect it either because this is a laptop. Is there any way to edit grub to allow bootable cds to boot?
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Expert Comment

by:rindi
ID: 16986689
Why can't you just remove the disk from the laptop? Usually this isn't too difficult. Are you sure the CD drive is OK?
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by:xberry
ID: 16990284
>>> Is there any way to edit grub to allow bootable cds to boot?

I can't see why GRUB should be the reason here for your problem.
The point is: Grub is located in the Master Booot sector of your hard disk, which means
that GRUB won't become activated unless your harddisk becomes available by
preference of your BIOS, or . . . rindi, how do you see that ?
What you're indicating would mean that the GRUB did modify
the BIOS ?
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by:rindi
ID: 16990330
Neither can I see why editing GRUB would help. If you remove the HD you'd eliminate the HD's bootsector from loading, maybe the boot sequence isn't correct or the BIOS is buggy and just won't boot from CD if there is a HD inside, or the CD drive isn't working. Without the disk inside you'd be able to troubleshoot that...
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by:xberry
ID: 16990395
Rindi's troubleshooting idea is something that you should try, how ever possible.

Just one thing coming to my mind: what type of BIOS of your's on that machine ?
How exactly does the sequence of bootable devices
look like in your BIOS setup, can you post it here ?
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by:xberry
ID: 16990554
Somehow I have attention to this one:

>> Normally, this laptop can boot from usb cd or dvd drives as it doesn't have an internal drive
>> I installed the FC on the laptop through an external drive.

Sure, nothing unusual for a laptop, also, I am not really the hardware specialist here,
but since I had issues with USB myself, only the thought that the BIOS not correctly
identifying the disk devices there. Rindi may help us here, my idea is:
when eggster34 did install FC to HD, the BIOS did reckognize two addresses
in this sequence:
1. external CDROM 2. HD-Drive
Then he does remove the external drive, reboots his system,
BIOS can't find external drive, some memory adresses get confused
and HD-Drive is mistaken for CDROM, so whenever he tries to boot from
CDROM it is simply mistaken for a different drive, but not the first it should be
in his boot sequence. A defect in the USB-bus system ? corrupt BIOS,
even thinking of  . . . EEPROM ?  Well, I mean if things would be perfect,
kinda surprisive issues like that would not happen. All I want to tell is,
the reason would rather lay in the fact of employing and disemploying external
drives to the system for purpose of installation and not in the installed software
itself.  


.
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Author Comment

by:eggster34
ID: 16992980
I will have to boot from this cd frequently. Is Rindi suggesting that I should open up my laptop and remove the drive each time I have to boot from the cd rom ? :)))
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Expert Comment

by:rindi
ID: 16993036
No, what I'm saying is to remove it now to find out where the problem lies and if the CD can boot. As I have already mentioned there could be a problem with the PC, or also the cd drive. Have you tried the drive in another pc, and can you boot the cd from there?
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Author Comment

by:eggster34
ID: 17014353
yes when I try the drive on another pc, it boots off just fine.
also, the same cd works on other pcs too. but bootable cds don't work on this machine anymore.
I'll remove the hdd and see what happens.
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Author Comment

by:eggster34
ID: 17053817
I figured it out. I had to hit the U button on the toshiba laptop to boot off usb.
it had nothing to do with grub etc.
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by:xberry
ID: 17056706
>>> I figured it out.

Well done ; )

>>> it had nothing to do with grub etc.

Which was what we told you, didn't we ? ; ))
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Expert Comment

by:rindi
ID: 17060407
OK with me.
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