Moving boot

[Les Mikesell]

Karl Larsen wrote:
> 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.

I read what you wrote when you quoted the explicit bios error message.

> Again, my /boot is 7,000 cylinders 
> from the start of hard drive 2 

As I pointed out, there have been other limits as bios evolved to match 
available hard disks.

> and the grub is on hard drive 1 MBR

A tiny part of grub is there. Several other stages are elsewhere.


> AND IT WORKS JUST FINE! NO PROBLEM AT ALL.

Then how did you get that error message about exceeding a bios limit to 
display?  And why have you been complaining about it for days?

-- 
   Les Mikesell
    lesmikesell at gmail.com