A strange occurrence

A strange occurrence

[David A. Cobb]

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  This isn't a development question, but I'm hoping the list's knowledge 
of GRUB will help me understand it.

Running Ubuntu 9.04, everything up-to-date, package "grub-pc" version 1.96+
GRUB-2 was installed after having GRUB 0.9x running for years.  The 
installation involved letting GRUB chainload GRUB-2 until I saw it was 
ready for primetime, then running an upgrade script.  I mention that 
because it's important to know that there is still a GRUB 0.9x image 
somewhere.

Trying to get past a nasty problem involving the interaction between a 
2003 Phoenix BIOS, and a big 160-GB disk that would not have been 
available in 2003.  I used BIOS setup to change the disk detection to 
manual, and made sure the numbers that came up were the same as after a 
successful boot.

Booted, and WHOA! I got the system-selection screen from GRUB 0.9x.  
But, it included versions of the kernel that were not installed until 
after I switched to GRUB-2.  Actually, the only thing I'm sure was 
"wrong" was the lack of a colorful splash image.  Well, no, actually, 
I'm fairly sure the console displays were not the same as the "WELCOME 
TO GRUB" that shows at the start of the GRUB-2 boot; but it goes past 
pretty quick, and I could be wrong about that.

So, maybe I hosed my GRUB-2 installation.  That wouldn't explain how a 
GRUB 0.9x image was found.  Anyway, I re-installed the package and 
(re)ran grub-install.  And rebooted.  And got the same screen.

So, eliminate the one variable I knew was changed: I reset the BIOS 
Setup to do automatic disk detection.  Voilla!!
I'm back with the GRUB-2 splash screen, and everything is cool.

But, I'm puzzled [yeah, that is my normal state].  Did the BIOS actually 
read a different image?  Or, did the "old" GRUB fail to chainload, even 
though there is no visible sign during a normal boot that the old GRUB 
is still around?  If the latter, should I consider writing the GRUB-2 
image onto the MBR again?  Or, would that be just asking for trouble?

TIA
-- 
David A. Cobb, computing t-rex.


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Re: A strange occurrence

[Felix Zielcke]

Am Dienstag, den 16.06.2009, 14:20 -0400 schrieb David A. Cobb:
> This isn't a development question, but I'm hoping the list's knowledge 
> of GRUB will help me understand it.
> 
> Running Ubuntu 9.04, everything up-to-date, package "grub-pc" version 1.96+
> GRUB-2 was installed after having GRUB 0.9x running for years.  The 
> installation involved letting GRUB chainload GRUB-2 until I saw it was 
> ready for primetime, then running an upgrade script.  I mention that 
> because it's important to know that there is still a GRUB 0.9x image 
> somewhere.
> 
> Trying to get past a nasty problem involving the interaction between a 
> 2003 Phoenix BIOS, and a big 160-GB disk that would not have been 
> available in 2003.  I used BIOS setup to change the disk detection to 
> manual, and made sure the numbers that came up were the same as after a 
> successful boot.
> 
> Booted, and WHOA! I got the system-selection screen from GRUB 0.9x.  
> But, it included versions of the kernel that were not installed until 
> after I switched to GRUB-2.  Actually, the only thing I'm sure was 
> "wrong" was the lack of a colorful splash image.  Well, no, actually, 
> I'm fairly sure the console displays were not the same as the "WELCOME 
> TO GRUB" that shows at the start of the GRUB-2 boot; but it goes past 
> pretty quick, and I could be wrong about that.
> 
> So, maybe I hosed my GRUB-2 installation.  That wouldn't explain how a 
> GRUB 0.9x image was found.  Anyway, I re-installed the package and 
> (re)ran grub-install.  And rebooted.  And got the same screen.
> 
> So, eliminate the one variable I knew was changed: I reset the BIOS 
> Setup to do automatic disk detection.  Voilla!!
> I'm back with the GRUB-2 splash screen, and everything is cool.
> 
> But, I'm puzzled [yeah, that is my normal state].  Did the BIOS actually 
> read a different image?  Or, did the "old" GRUB fail to chainload, even 
> though there is no visible sign during a normal boot that the old GRUB 
> is still around?  If the latter, should I consider writing the GRUB-2 
> image onto the MBR again?  Or, would that be just asking for trouble?

upgrade-from-grub-legacy currently runs grub-install '(hd0)' and which
disk hd0 is, is defined in your /boot/grub/device.map
Robert and me are thinking how we solve that problem at best.
If you tell grub-pc that you want to chainload it from grub-legacy then
it runs the update-grub from grub-legacy to create the menuentry for it
and so updates the kernel list for it too.
Maybe you just had grub-legacy in MBR of 2 (or more) of your disks
installed and then BIOS just loaded not the one you thought it would but
the other one.
I don't see where grub2 would have a problem.
If your BIOS changes the disk order then you have to make sure that on
this disk the right grub is installed to MBR.
-- 
Felix Zielcke

Re: A strange occurrence

[BandiPat]

David A. Cobb wrote:
>  This isn't a development question, but I'm hoping the list's knowledge 
> of GRUB will help me understand it.
> 
> Running Ubuntu 9.04, everything up-to-date, package "grub-pc" version 1.96+
> GRUB-2 was installed after having GRUB 0.9x running for years.  The 
> installation involved letting GRUB chainload GRUB-2 until I saw it was 
> ready for primetime, then running an upgrade script.  I mention that 
> because it's important to know that there is still a GRUB 0.9x image 
> somewhere.
> 
> Trying to get past a nasty problem involving the interaction between a 
> 2003 Phoenix BIOS, and a big 160-GB disk that would not have been 
> available in 2003.  I used BIOS setup to change the disk detection to 
> manual, and made sure the numbers that came up were the same as after a 
> successful boot.
> 
> Booted, and WHOA! I got the system-selection screen from GRUB 0.9x.  
> But, it included versions of the kernel that were not installed until 
> after I switched to GRUB-2.  Actually, the only thing I'm sure was 
> "wrong" was the lack of a colorful splash image.  Well, no, actually, 
> I'm fairly sure the console displays were not the same as the "WELCOME 
> TO GRUB" that shows at the start of the GRUB-2 boot; but it goes past 
> pretty quick, and I could be wrong about that.
> 
> So, maybe I hosed my GRUB-2 installation.  That wouldn't explain how a 
> GRUB 0.9x image was found.  Anyway, I re-installed the package and 
> (re)ran grub-install.  And rebooted.  And got the same screen.
> 
> So, eliminate the one variable I knew was changed: I reset the BIOS 
> Setup to do automatic disk detection.  Voilla!!
> I'm back with the GRUB-2 splash screen, and everything is cool.
> 
> But, I'm puzzled [yeah, that is my normal state].  Did the BIOS actually 
> read a different image?  Or, did the "old" GRUB fail to chainload, even 
> though there is no visible sign during a normal boot that the old GRUB 
> is still around?  If the latter, should I consider writing the GRUB-2 
> image onto the MBR again?  Or, would that be just asking for trouble?
> 
> TIA
> 
> _______________________________________________

David, I'll just add this to what Felix has told you, because it does 
indeed sound like you had the old grub-legacy installed to the MBR of 
more than one of your drives.

Since I've been playing with Grub2 SVN, I've come to find that the 
constant writing to the MBR can go awry, causing strange things with the 
hard drive.  At one point, I thought my drive was bad, but turned out 
the MBR was just confused.  What I do now is to clear out the MBR every 
other update to be sure I get a clean install of the latest Grub2.

Here's what you do from a root shell:
dd if=/dev/zero of=/dev/sdx bs=446 count=1
(the "x" is the letter of your installed drive, "a" "b" )
Also, for the "bs" number, never use more than "446" as anything larger 
will overwrite your partition table of the drive, pretty much rendering 
it useless without any partitions.

What it does is write zero's to the MBR of the drive, overwriting any 
info there.  Then you can run your "grub-install /dev/sdx" to install 
Grub2 to your MBR of the booting drive.

Hopefully helpful,
Pat


-- 
        ---Zenwalk v6.0--Linux 2.6.28---
         Registered Linux User #225206
"Ever tried Zen computing?"  http://www.zenwalk.org

Re: A strange occurrence

[Vladimir 'phcoder' Serbinenko]

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On Tue, Jun 16, 2009 at 9:38 PM, BandiPat <magicpage91@earthlink.net> wrote:

> David A. Cobb wrote:
>
>>  This isn't a development question, but I'm hoping the list's knowledge of
>> GRUB will help me understand it.
>>
>> Running Ubuntu 9.04, everything up-to-date, package "grub-pc" version
>> 1.96+
>> GRUB-2 was installed after having GRUB 0.9x running for years.  The
>> installation involved letting GRUB chainload GRUB-2 until I saw it was ready
>> for primetime, then running an upgrade script.  I mention that because it's
>> important to know that there is still a GRUB 0.9x image somewhere.
>>
>> Trying to get past a nasty problem involving the interaction between a
>> 2003 Phoenix BIOS, and a big 160-GB disk that would not have been available
>> in 2003.  I used BIOS setup to change the disk detection to manual, and made
>> sure the numbers that came up were the same as after a successful boot.
>>
>> Booted, and WHOA! I got the system-selection screen from GRUB 0.9x.  But,
>> it included versions of the kernel that were not installed until after I
>> switched to GRUB-2.  Actually, the only thing I'm sure was "wrong" was the
>> lack of a colorful splash image.  Well, no, actually, I'm fairly sure the
>> console displays were not the same as the "WELCOME TO GRUB" that shows at
>> the start of the GRUB-2 boot; but it goes past pretty quick, and I could be
>> wrong about that.
>>
>> So, maybe I hosed my GRUB-2 installation.  That wouldn't explain how a
>> GRUB 0.9x image was found.  Anyway, I re-installed the package and (re)ran
>> grub-install.  And rebooted.  And got the same screen.
>>
>> So, eliminate the one variable I knew was changed: I reset the BIOS Setup
>> to do automatic disk detection.  Voilla!!
>> I'm back with the GRUB-2 splash screen, and everything is cool.
>>
>> But, I'm puzzled [yeah, that is my normal state].  Did the BIOS actually
>> read a different image?  Or, did the "old" GRUB fail to chainload, even
>> though there is no visible sign during a normal boot that the old GRUB is
>> still around?  If the latter, should I consider writing the GRUB-2 image
>> onto the MBR again?  Or, would that be just asking for trouble?
>>
>> TIA
>>
>> _______________________________________________
>>
>
> David, I'll just add this to what Felix has told you, because it does
> indeed sound like you had the old grub-legacy installed to the MBR of more
> than one of your drives.
>
> Since I've been playing with Grub2 SVN, I've come to find that the constant
> writing to the MBR can go awry, causing strange things with the hard drive.
>  At one point, I thought my drive was bad, but turned out the MBR was just
> confused.  What I do now is to clear out the MBR every other update to be
> sure I get a clean install of the latest Grub2.
>
> Here's what you do from a root shell:
> dd if=/dev/zero of=/dev/sdx bs=446 count=1
> (the "x" is the letter of your installed drive, "a" "b" )
> Also, for the "bs" number, never use more than "446" as anything larger
> will overwrite your partition table of the drive, pretty much rendering it
> useless without any partitions.
>
440, not 446, otherwise you destroy serial number of the drive

>
> What it does is write zero's to the MBR of the drive, overwriting any info
> there.  Then you can run your "grub-install /dev/sdx" to install Grub2 to
> your MBR of the booting drive.
>
> Hopefully helpful,
> Pat
>
>
> --
>       ---Zenwalk v6.0--Linux 2.6.28---
>        Registered Linux User #225206
> "Ever tried Zen computing?"  http://www.zenwalk.org
>
>
>
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/grub-devel
>



-- 
Regards
Vladimir 'phcoder' Serbinenko

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Re: A strange occurrence

[Felix Zielcke]

Am Dienstag, den 16.06.2009, 15:59 -0400 schrieb BandiPat:
> Vladimir 'phcoder' Serbinenko wrote:
> 
> >     Here's what you do from a root shell:
> >     dd if=/dev/zero of=/dev/sdx bs=446 count=1
> >     (the "x" is the letter of your installed drive, "a" "b" )
> >     Also, for the "bs" number, never use more than "446" as anything
> >     larger will overwrite your partition table of the drive, pretty much
> >     rendering it useless without any partitions.
> > 
> > 440, not 446, otherwise you destroy serial number of the drive
> ============
> Thanks phcoder,
> Each time I find info about doing this, I also find more info about how 
> much to write.  I used 512 the first time I did it, quickly learning I 
> cleared out my partition table, then I found the 446 after I had to 
> rebuild my drive from scratch.  :-\
> 
> I had not found anything about the 440, but it's good to know so as not 
> to remove any pertinent drive data.
> 

You'd only need to look at the wikipedia MBR page for this:
http://en.wikipedia.org/wiki/Master_boot_record
-- 
Felix Zielcke

Re: A strange occurrence

[BandiPat]

Vladimir 'phcoder' Serbinenko wrote:

>     Here's what you do from a root shell:
>     dd if=/dev/zero of=/dev/sdx bs=446 count=1
>     (the "x" is the letter of your installed drive, "a" "b" )
>     Also, for the "bs" number, never use more than "446" as anything
>     larger will overwrite your partition table of the drive, pretty much
>     rendering it useless without any partitions.
> 
> 440, not 446, otherwise you destroy serial number of the drive
============
Thanks phcoder,
Each time I find info about doing this, I also find more info about how 
much to write.  I used 512 the first time I did it, quickly learning I 
cleared out my partition table, then I found the 446 after I had to 
rebuild my drive from scratch.  :-\

I had not found anything about the 440, but it's good to know so as not 
to remove any pertinent drive data.

Pat

Re: A strange occurrence

[BandiPat]

Felix Zielcke wrote:

> You'd only need to look at the wikipedia MBR page for this:
> http://en.wikipedia.org/wiki/Master_boot_record
-----------
And where were you when I needed all this data!  ;-)

I did all kinds of searches, but didn't find this info.  As I mentioned, 
I found the 512 bytes first, then 446, so that's what I've been using. 
Anyway, thanks for the additional info and Wiki site.  I should learn to 
search for the Wiki sites right away.  :-/

Pat

-- 
        ---Zenwalk v6.0--Linux 2.6.28---
         Registered Linux User #225206
"Ever tried Zen computing?"  http://www.zenwalk.org

Re: A strange occurrence

[David A. Cobb]

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  On 06/16/2009 02:30 PM, Felix Zielcke wrote:
> Am Dienstag, den 16.06.2009, 14:20 -0400 schrieb David A. Cobb:
>> <BIG SNIP/>
>>
>> But, I'm puzzled [yeah, that is my normal state].  Did the BIOS actually
>> read a different image?  Or, did the "old" GRUB fail to chainload, even
>> though there is no visible sign during a normal boot that the old GRUB
>> is still around?  If the latter, should I consider writing the GRUB-2
>> image onto the MBR again?  Or, would that be just asking for trouble?
> upgrade-from-grub-legacy currently runs grub-install '(hd0)' and which
> disk hd0 is, is defined in your /boot/grub/device.map
> Robert and me are thinking how we solve that problem at best.
OK. I only have one disk, and I did "upgrade-from-grub-legacy."
> If you tell grub-pc that you want to chainload it from grub-legacy then
> it runs the update-grub from grub-legacy to create the menuentry for it
> and so updates the kernel list for it too.
> Maybe you just had grub-legacy in MBR of 2 (or more) of your disks
> installed and then BIOS just loaded not the one you thought it would but
> the other one.
> I don't see where grub2 would have a problem.
> If your BIOS changes the disk order then you have to make sure that on
> this disk the right grub is installed to MBR.
MfG!
David

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