Grub and logical partitions

Daniel B. Thurman dant at cdkkt.com
Sat Jul 31 01:56:10 UTC 2010


On 07/30/2010 06:37 PM, Frantisek Hanzlik wrote:
> Timothy Murphy wrote:
>   
>> Can grub boot from a logical partition?
>>
>> It seems from my reading that it cannot.
>>
>> But I found that I could in fact boot from /dev/sda5
>> if I used grub interactively, starting with
>>    root (hd0,4)
>> then using tab to look for kernel and initrd
>> and finally booting.
>>
>> However, if I put exactly the same commands in grub.conf
>> the boot failed, with "File not found ...".
>>
>> (Nb I am not using LVM, sda5 is a logical partition
>> within the extended partition sda4.)
>>
>> Can some guru explain this to me please.
>>     
> I'm using legacy grub1 for booting from logical partitions (ext2/ext3 
> and now ext4) routinely long since early Fedora (maybe Redhat 7.x/8/9) 
> versions, already without problems.
>
> But just now on F13 i686 I run across other, maybe similar problem:
> I install it on /dev/sda8 (sda is 200GB SATA drive, DOS type partition 
> table, grub installed in MBR), installation passed OK. But when booting, 
> grub not print any error, but display stage2 message:
>
>      GNU GRUB  version 0.97  (639K lower / 1047488K upper memory)
>
>   [ Minimal BASH-like line editing is supported.  For the first word, TAB
> lists possible command completions.  Anywhere else TAB lists the possible
> completions of a device/filename.
>
>
> It seems to me as if it could not find configfile. But, when I type 
> "root (hd0,7)" and "configfile /boot/grub/grub.conf" (or "configfile 
> /boot/grub/menu.lst"), then normally appears f13 grub splash screen with 
> menu items and after selecting one grub correctly boot it.
>
> - reinstalling grub ( "root (hd0,7)" and then "setup [--force-lba] 
> (hd0)" does not help.
>
> - when I restore grub for Fedora 12, which is installed on /dev/sda7 (in 
> same manner: "root (hd0,7)" and then "setup (hd0)" ), then grub works fine.
>
> - only thing which hit me is about accessing files beyond 137 GB (28 bit 
> LBA limit), as sda8 partition lies at <117GB,144GB>. But - on other i686 
> PC I have F12 on /dev/sda10 (sda10 partition start on 128GB and ends at 
> 148GB) and F13 on /dev/sda9, and both are bootable via grub1 without 
> problems. Moreover, I think, when there would be 28-bit addressing 
> problem, then nor handy specification should be successfull.
>
> Some grub1 guru should be likely in Fedora/Redhat suite, as grub1 is 
> stated as legacy and isn't supported :) ?
>
> Franta
>   
I did not state it in my previous thread, but I am using 2 TiB drives
which is well beyond the boundary - also - I have windows 2k, XP,
and Vista (no problems) but very special care must be taken into
consideration dealing with w2K - but that is legacy anyway.

As for grub2, grub1 does boot grub2, so as long as the MBR for
that grub2 boot partition is MBR set, but as it is, it is hard to figure
out just how to do this manually, as I was only able to install MBR for
the grub2 boot partition via Ubuntu's LiveCD installer and have yet to
learn from the Ubuntu community just how to do that.



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