Re: GRUB woes (install to hde)

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Date: Thu, 29 Sep 2005 16:43:36 -0500
To: debian-user@lists.debian.org

Alvin Oga wrote:
>
> On Thu, 29 Sep 2005, Mike McCarty wrote:
>
>
>>>it'd be pointless to install the grub mbr on /dev/hde if it cannot boot
>>
>>Umm, no, what he's doing is perfectly reasonable.
>
>
> if doesn't work ... one should figure out technically why it will
> not work
> - some bios will NTO let you boot from /dev/hde is all
> i'm saying and since it is a "grub woes" what does grub do
> for you in this case, esp if as you say, he's not booting it ??
>
>
>>He wants to
>>duplicate boot discs for use on other machines.
>
>
> ah... more grub problems ..

Yeah. Well, not problems. Just want to install using a technique
GRUB isn't deliberately set up for.

> you cannot move a /dev/hde w/ grub info already on it from PC#1
> to boot it as /dev/hda on PC#2 and expect pc#2 to boot it
> - explain why ... you can .. and under what circumstances
> you can boot

Of course he can't just do that. Nobody has said he could.
The trick is to figure out a way to accomplish the end goal,
which is to be able to put a disc into a machine, type a command
or three, and in several minutes have a disc which can be used
that way. THAT is what I think is the goal, and I also think it is
reasonable to want to do. And I'm sure there is a way to
do it. Just haven't figured it out, yet :-)

> - same disk config or different disk config in terms of
> the number and ordering of fd, cd, dvd, ide, scsi
> and also referring to /boot/grub/device.map
>
> - since you're moving from /dev/hde which presumably
> implies you booted a different disk that you're trying to
> clone... you will have problems as /dev/hde become /dev/hda
> but is trivially fixed in 5 seconds if you know what to
> change .. and with grub you do NOT need to edit files
> and can change it dynamically to test it

Yep.

>
>>IIUI, he doesn't want to boot from /dev/hde ever.
>
>
> which gets back to the point .. why bother with grub in that case

He wants GRUB on the /dev/hda when he moves the disc to the
new machine. He wants GRUB to manage the boot from the disc
he's making. At some point, GRUB needs to be installed
somewhere.

>>He wants to create a disc
>>connected as /dev/hde which can become /dev/hda on another
>>machine.
>
>
> and again .. why ???

Because he has lots of machines to install on. I forget the
number, if he even mentioned it exactly, but the impression I get
is tens of machines with identical or nearly identical discs.

He wants a disc duplicator which will duplicate a bootable hard
disc.

>
> - it's a lot of headache when there are trivially 100x simpler
> ways of doing the same thing
>
>
>>One way to do that would be to dd if=zero of=/dev/hda ...
>
>
> that could be the equivalent of " rm -rf " if one were to use
> that command without knowing what it might do

Umm, no. This was in context of copying the device. If the device is not
filled with zeroes, then the compression doesn't work so well,
and that would result in very large file.

>>and then make the thing a minimal bootable, then put it on
>>as, say, /dev/hdf and then dd if=/dev/hdf | gzip image to create a
>>(relatively) small image on /dev/hda.
>
>
> now you have /dev/hdf to create what would be /dev/hda on /dev/hde
> ( more complications )
>
>
>>I've tried to figure out a way he can clone his boot for him without
>>writing multi-megs of data. It should be easy, but isn't, quite.
>
>
> to clone any boot info from any disk to another ..
>
> dd if=/dev/hda of=/dev/hdc bs=446 count=1
>
> where you want /dev/hda to be the way the clone will boot
> when /dev/hdc will become /dev/hda later in a different
> or same box

And that causes /dev/hdc to have Linux installed on it how?

> converting hda to hdc is a imple matter of changing fstab

Well, this isn't what I think he wants to do.

He has, say, twenty virtually identical machines with Some Other
OS installed on them. Call these machines B-U.

He wants to take the hard drive out of each, say one or two at
a time, and put them into a machine which already runs Our Favorite OS.
Call this machine A. So he takes the disc out of machine B, and puts
it into machine A, and boots.

He then would like to issue a few commands, which hopefully run in a
reasonable amount of time, after which he can take the disc originally
from disc B back out of machine A, and put it into machine B, which
then automagically is a Linux booting machine. Then he'd like to repeat
this with the disc currently in machine C, making machine C a Linux
machine. And so on.

This is what I understand to be the goal. It's a reasonable one.
And I'm pretty sure it's achievable. One just has to hold his
tongue right.

There may be a better way to clone off machines. Maybe you even
know one.

> - there are say hundred ways to make a bootable disk
> and NOT all will work in all situations

Well, that's pretty much evident.

Mike

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