Upgrade procedure/advice: boot sector

[Jeff Vian]

Don Levey wrote:

>On Sat, 2004-05-22 at 23:58, Jeff Vian wrote:
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>>Don Levey wrote:
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>>>I decided that, given a slow weekend, I would upgrade my personal
>>>mail/web server from RedHat9 to Fedora2.  Wanting to minimise problems,
>>>I did what I hoped would a complete, sector-for-sector copy of the main
>>>disk onto another disk of the same geometry using:
>>>       dd if=/dev/hda of=/dev/hdb
>>>
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>>This may be because you said you did a "sector-for-sector copy of the 
>>main disk onto another disk of the same geometry using: dd if=/dev/hda 
>>of=/dev/hdb"
>>This should always work *IF AND ONLY IF* the drives are exactly the same 
>>geometry.  That means same physical construciton, and even same make, 
>>model, (and maybe even same firmware levels).  If the geometry is not 
>>exactly the same it *MAY* work.  
>>What you in effect have done is create an exact *byte-for-byte* copy of 
>>the drive, including boot sector, partiton table, and even the otherwise 
>>inaccessible data that handles LBA mapping, etc.  If this changed 
>>information happens to be incompatible with the new hardware it can 
>>fail; particularly if the boot sector is not where the drive firmware 
>>expects it to be.
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>Well, they both *say* that they're the same.  It's certainly the same
>model and manufacturer, but I guess they could have changed the internal
>geometry even if the numbers match up. 
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>>I assume from what you have said, that the drive is accessible in all 
>>ways /except that  it will not boot/.  As such I would suspect a 
>>geometry problem that confuses the drive firmware during boot and before 
>>Linux gets loaded.
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>I was just thinking: " I'm curious, though - would this explain being
>able to access other files on the disk *except* the boot?" so I guess
>the answer would be "yes."
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>>>Should I:
>>>1) Just boot to the Fedora CDs and run the upgrade?  Would this install
>>>the boot loader for me? Or...
>>>2) Work harder at getting the new disk to boot first, and then do the
>>>upgrade?
>>> 
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>>Maybe you should rewrite the partiton table on the new drive and then 
>>copy partiton-by-partition to that drive.
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>That sounds like the next step, I guess.  I may take the time to
>readjust the partition sizes, at that point.  None of my family actually
>does work on this machine, so having a large /home doesn't seem to make
>sense.  However, I've got quite a bit on the web server (family
>pictures, and all that) as well as the entire CD collection in a media
>directory.  So /var may grow a bit.  Thanks for the help!
> -Don
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One more thought.

You did not say whether you were reconnecting the second drive (hdb) in 
as the master (hda) before attempting to boot.  Your copy method makes 
an exact copy of the original, and it should have the mbr and everything 
else the same.

Try removing the original hda drive and putting the second drive in that 
position and see if it will boot.

Jeff

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