External HD install: No OS found error

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External HD install: No OS found error

Postby tigger on Sat Jan 19, 2008 2:43 pm

Ok, I was trying to install onto my external hard drive, with the desired outcome that I could turn on my laptop with the ext HD plugged in, and boot mint, but when it wasn't plugged in, it would boot straight to windows.

So, I burned a live cd, unplugged my internal drive, installed mint+grub to the external drive, and booted back up (still without the internal drive plugged in). Everything loaded fine, I was happy. I plugged the internal drive in, and booted windows:perfect. However, now that I have both the internal and external plugged in, I can't boot either! I've tried disabling the internal drive in the BIOS as a quick fix to boot linux, but that doesn't make any difference. I can only boot linux with the internal unplugged, and I can only boot windows with the external unplugged. This is of course, hardly ideal.
(and no, I cannot install to the internal HD or anything like that, so please don't suggest it)

I'm sure I installed correctly, so what's going wrong? :confused:


Thanks for your help.
tigger
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Re: External HD install: No OS found error

Postby Husse on Sat Jan 19, 2008 5:00 pm

Well that's about what I would expect to happen if you can't change boot order in BIOS, which is not to be expected in a laptop
How would the boot order be decided....
But there is a solution - luckily
Download and burn Supergrub (google for it) to a CD (its about 4 MB so that download is no problem)
Then use supergrub to install grub.
Alternatively you could make manual changes to menu.lst in the existing grub.
With XP in the first partition as you have you should add
Code: Select all
title      Microsoft Windows XP Professional
root      (hd0,0)
savedefault
makeactive
chainloader   +1

Then follow this wiki
http://www.linuxmint.com/wiki/index.php ... _your_grub
Perhaps as easy to do as Supergrub and you learn some
There is a but. If this had been two different Linux, perhaps the one on the internal drive would complain if the USB drive was not connected but would continue booting
XP being less sophisticated and called upon in a different way from grub would not even notice it
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Re: External HD install: No OS found error

Postby tigger on Sat Jan 19, 2008 5:37 pm

I can change the boot order: it *should* boot from the external drive, but doesn't. Also, I realized that the OS not found error was because I forgot to re-enable the internal drive (now that it's enabled, it boots straight to windows)

Do you think I should try reinstalling grub to the external anyway?
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Re: External HD install: No OS found error

Postby Husse on Sat Jan 19, 2008 7:09 pm

Now that's surprising....
You set USB to boot first and yet it does not? Semi hardware error (wont go into the details of booting :))
Grub is already on your USB drive
I need to explain a bit
You will find a folder /boot that contains grub and in dual boot with XP that's on the Linux partition
I think you know that
When we talk about putting Grub on this or that disk (like you can do when you install from the "Advanced" button in the las dialog box) it's grub stage one which is a miniscule (only a few hundred bytes) program.
You should have that on the internal disk, and then of course you need something to start windows from the later stages of grub. I don't think you have that now as you installed with the XP disk disconnected, so you can use my suggestion to fix that little problem
So booting will always start with the internal drive, but you are given the choice to decide where it will continue
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Re: External HD install: No OS found error

Postby tigger on Sun Jan 20, 2008 5:57 am

* I repared GRUB the way the wiki said
* I put the windows part into the menu.lst

This fixed the problem! However, after I rebooted, it did not seem to save these changes :? :|
Upon reboot, it was back the way it was before :(


I would like to have it set up that I can boot to linux with the ext hard disc, without altering the windows install/internal HD at all, and its proving pretty complicated :(
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Re: External HD install: No OS found error

Postby tigger on Sun Jan 20, 2008 7:45 am

In the BIOS, the boot sequence is

Removable Devices
+Hard Drive
Seagate FreeAgent Pro <-- the external drive
BLAHBLAHBLAH <-- the internal drive
Cd drive


This (I think) means that it should boot from the external hard drive, but it doesn't: it simply skips it, and moves to the internal (booting windows).

However, in the BIOS, the two hard drives are both listed as master: primary master, and secondary master. The external is the secondary master. Do you think changing the external to be primary master would fix it? and how do I do that?

thanks for your help.
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Re: External HD install: No OS found error

Postby Husse on Sun Jan 20, 2008 1:47 pm

Did you do it exactly as stated in the wiki (with necessary changes for your needs of course)?
Have you checked the menu.lst?
Must ask this because this is crazy
When I write this a thought hit me (hard :))
This is not used these days, but do you have some Boot sector protection/antivirus?
That blocks writing to MBR
Check BIOS and disable it if it is enabled and repeat the repair grub stages.
You should not have to add XP in menu.lst again
If you do not have that enabled it is either a hidden Boot sector protection or a virus in MBR (or very unlikely some special boot sector that can't be handled in normal ways)
All this is said presuming it is not an Apple laptop, because that changes the entire scenario
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