Moving boot

Karl Larsen k5di at zianet.com
Mon Aug 20 17:57:22 UTC 2007


Les Mikesell wrote:
> Karl Larsen wrote:
>
>>>>>> I now have the /boot part of my whole system. But it would be 
>>>>>> easy to make a new partition of say 100 MB the first thing on the 
>>>>>> second hard drive. My question is what do I need to do so the new 
>>>>>> /boot works?
>>>>>>     
>>>>>
>>>>> I did something similar with a dual-boot system:  Windows on the
>>>>> original first drive, all by itself.  And Linux installed on an added
>>>>> second drive, all by itself.
>>>>>
>>>>> While setting up GRUB, you define its root (where /boot/ is) with a
>>>>> "root (hd1,0)", then "setup (hd0)" which puts the bootloader onto the
>>>>> first drive MBR, and quit out of the GRUB shell.
>>>>>
>>>>> [root at bigblack ~]# grub
>>>>> grub> root (hd1,0)
>>>>> grub> setup (hd0)
>>>>> grub> quit
>>>>> [root at bigblack ~]#
>>>>>
>>>>> In this scenario, the computer boots, reads the MBR on my first 
>>>>> drive,
>>>>> which starts off GRUB from my second drive.
>>>>>
>>>>> I believe that you can even set that up from within the GRUB start up
>>>>> screen.  Just hit the right hot key to get into the command line.  
>>>>> You
>>>>> can also do it from the rescue disc, so you can get a system working
>>>>> that's not currently booting.
>>>>>
>>>>>   
>>>>    I know Tim and that is what I use now that works. I have grub at 
>>>> (hd0) and the Linux is at (hd1,5). This works fine so why move /boot?
>>>>
>>>>    I am certain that (hd1,5) is about 100 GB up from start of the 
>>>> second drive. And it works.
>>>
>>> I thought this whole thread was about this setup not working all the 
>>> time.  What does fdisk -l say about the cylinder range of that 5th 
>>> partition?
>>>
>>    Well it is the sixth partition. This is (hd1,5) in grub talk :-)
>>
>>
>> Disk /dev/sdb: 160.0 GB, 160041885696 bytes
>> 255 heads, 63 sectors/track, 19457 cylinders
>> Units = cylinders of 16065 * 512 = 8225280 bytes
>>
>>   Device Boot      Start         End      Blocks   Id  System
>> /dev/sdb1   *           1        1217     9775521   83  Linux
>> /dev/sdb2            1218        1945     5847660   83  Linux
>> /dev/sdb3            1946        1961      128520   82  Linux swap / 
>> Solaris
>> /dev/sdb4            1962       18534   133122622+   5  Extended
>> /dev/sdb5            1962        7060    40957686   83  Linux
>> /dev/sdb6            7061       12159    40957686   83  Linux
>> /dev/sdb7           12160       18534    51207156   83  Linux
>> [root at k5di ~]#
>>
>> Now you can see sdb6 starts at cylinder 7061 which the hell and gone 
>> above 1100 :-(
>>
>>
>> So thanks for the idea for quantizing the fact. I think it's clear my 
>> 1994 BIOS works far better than the so-called standard. 8-)
>
> The hard drive addressing limits in bios have evolved slowly and 
> painfully over time starting from 32 Megs in DOS.  The next limit 
> after 1024 cylinders was a 24 bit LBA address which would take you to 
> around 128 gigs. http://en.wikipedia.org/wiki/Logical_Block_Addressing
>
> I didn't do the math, but that error message you posted leaves no 
> doubt that you are exceeding the bios limit when you can't boot so 
> your 6th partition must span that range.  But, regardless of what the 
> limit actually turns out to be, you could have easily avoided any such 
> problem by putting a small /boot at the beginning of the disk, 
> something that has been well known since the first drives over 9 gigs 
> were manufactured.
>
Les you do not read what I wrote. Again, my /boot is 7,000 cylinders 
from the start of hard drive 2 and the grub is on hard drive 1 MBR

AND IT WORKS JUST FINE! NO PROBLEM AT ALL.

-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.




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