Grub and logical partitions

Daniel B. Thurman dant at cdkkt.com
Sat Jul 31 02:00:09 UTC 2010


On 07/30/2010 06:51 PM, Frantisek Hanzlik wrote:
> 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 forgot to tell - all my above mentioned Fedora installations occupies 
> one partition, I have no extra "/boot/" partitions.
> Franta
>   
Well, I used a separate /boot partition because in the past somehow,
grub or partition MBR got lost when something changed via an update.
Maybe this a non-issue by now?



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