grub question - Setup

This is a discussion on grub question - Setup ; Bonjour, I have two HD (sda sdb) and grub installed on the sda MBR. I want to install grub on the sdb MBR because the system is installed on the sdb HD. At this time, sdb is formatted like this: ...

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  1. grub question

    Bonjour,

    I have two HD (sda sdb) and grub installed on the sda MBR.

    I want to install grub on the sdb MBR because the system is installed on
    the sdb HD.

    At this time, sdb is formatted like this:

    / on sdb1

    the remaining of this drive is a part of a lvm gathering this remaining
    and a 3rd disk (sdc)

    sda has an extended linux partition with / on sda5 and /boot on sda6
    this disk was used in a previous install and is no more in use now,
    except the MBR and the grub.conf file which located in /boot/grub (on sda6).

    I want to re-format this sda to use it for backups and some other
    things, so I have to move the grub.conf somewhere else (/boot/grub on sdb1).

    How can I proceed?

    Thanks.
    --
    François Patte
    Université Paris 5 - Paris

  2. Re: grub question

    François Patte wrote:

    > Bonjour,
    >
    > I have two HD (sda sdb) and grub installed on the sda MBR.
    >
    > I want to install grub on the sdb MBR because the system is installed on
    > the sdb HD.
    >
    > At this time, sdb is formatted like this:
    >
    > / on sdb1
    >
    > the remaining of this drive is a part of a lvm gathering this remaining
    > and a 3rd disk (sdc)
    >
    > sda has an extended linux partition with / on sda5 and /boot on sda6
    > this disk was used in a previous install and is no more in use now,
    > except the MBR and the grub.conf file which located in /boot/grub (on
    > sda6).
    >
    > I want to re-format this sda to use it for backups and some other
    > things, so I have to move the grub.conf somewhere else (/boot/grub on
    > sdb1).
    >
    > How can I proceed?


    I don't really see any problem.
    There are 2 bits of grub;
    the actual loader which normally goes in the MBR,
    and the support files.
    You could install grub in the sdb MBR,
    provided your BIOS allows you to boot from sdb.
    (You will be offered a choice if you go into the BIOS at boot time.)

    But there is no reason why you should not have grub in the sda MBR
    and /boot with the grub support files on sdb.

    Maybe I misunderstood the question.

    --
    Timothy Murphy
    e-mail (<80k only): tim /at/ birdsnest.maths.tcd.ie
    tel: +353-86-2336090, +353-1-2842366
    s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

  3. Re: grub question

    Timothy Murphy a écrit :
    > François Patte wrote:
    >
    >> Bonjour,
    >>
    >> I have two HD (sda sdb) and grub installed on the sda MBR.
    >>
    >> I want to install grub on the sdb MBR because the system is installed on
    >> the sdb HD.
    >>
    >> At this time, sdb is formatted like this:
    >>
    >> / on sdb1
    >>
    >> the remaining of this drive is a part of a lvm gathering this remaining
    >> and a 3rd disk (sdc)
    >>
    >> sda has an extended linux partition with / on sda5 and /boot on sda6
    >> this disk was used in a previous install and is no more in use now,
    >> except the MBR and the grub.conf file which located in /boot/grub (on
    >> sda6).
    >>
    >> I want to re-format this sda to use it for backups and some other
    >> things, so I have to move the grub.conf somewhere else (/boot/grub on
    >> sdb1).
    >>
    >> How can I proceed?

    >
    > I don't really see any problem.
    > There are 2 bits of grub;
    > the actual loader which normally goes in the MBR,
    > and the support files.
    > You could install grub in the sdb MBR,
    > provided your BIOS allows you to boot from sdb.
    > (You will be offered a choice if you go into the BIOS at boot time.)
    >
    > But there is no reason why you should not have grub in the sda MBR
    > and /boot with the grub support files on sdb.


    I suppose that what you call "support files" is the /boot/grub/grub.conf
    isn't it? So how do I tell grub, installed in the sda MBR to query its
    configuration file in /boot/grub which is located in sdb1?

    Thanks.

    --
    François Patte
    Université Paris 5 - Paris

  4. Re: grub question

    François Patte wrote:

    > I suppose that what you call "support files" is the /boot/grub/grub.conf
    > isn't it?


    Exactly

    > So how do I tell grub, installed in the sda MBR to query its
    > configuration file in /boot/grub which is located in sdb1?


    By the "root" line in the grub entry.
    Here is an entry in my grub.conf,
    telling the machine that /boot is the second partition on /dev/sdb ,
    ie /dev/sdb2 .

    title Fedora (2.6.21-1.3228.fc7)
    root (hd1,1)
    kernel /vmlinuz-2.6.21-1.3228.fc7 ro root=/dev/VolGroup00/slash
    initrd /initrd-2.6.21-1.3228.fc7.img

    The hd1 means second disk.

    If you have a /boot partition at sdb1 you would say
    root (hd1,0)

    Note that if you do not have a separate partition for /boot
    (ie it is in the / partition)
    then you would say "kernel /boot/vmlinuz..." and "initrd /boot/initrd...".



    --
    Timothy Murphy
    e-mail (<80k only): tim /at/ birdsnest.maths.tcd.ie
    tel: +353-86-2336090, +353-1-2842366
    s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

  5. Re: grub question

    Timothy Murphy a écrit :
    > François Patte wrote:
    >
    >> I suppose that what you call "support files" is the /boot/grub/grub.conf
    >> isn't it?

    >
    > Exactly
    >
    >> So how do I tell grub, installed in the sda MBR to query its
    >> configuration file in /boot/grub which is located in sdb1?

    >
    > By the "root" line in the grub entry.
    > Here is an entry in my grub.conf,
    > telling the machine that /boot is the second partition on /dev/sdb ,
    > ie /dev/sdb2 .
    >
    > title Fedora (2.6.21-1.3228.fc7)
    > root (hd1,1)
    > kernel /vmlinuz-2.6.21-1.3228.fc7 ro root=/dev/VolGroup00/slash
    > initrd /initrd-2.6.21-1.3228.fc7.img
    >
    > The hd1 means second disk.


    I am not sure to understand the way grub is reading this grub.conf file...

    for me, grug is installed on sda MBR and read this file on /dev/sda6/grub
    (in "grub language": (hd0,5)/grub)

    while the system is installed on sdb and the beginning of my grub.conf is:

    title Fedora Core 6 (2.6.20-1.2952.fc6)
    root (hd1,0)
    kernel /boot/vmlinuz-2.6.20-1.2952.fc6 root=LABEL=/1 rhgb quiet
    initrd /boot/initrd-2.6.20-1.2952.fc6.img

    Shall I just move the directory (hd0,5)/grub into (hd1,0)/grub and at
    the next boot grub, which stays on sda MBR, will find it without any
    problem? I doubt.

    Thanks for attention.

    --
    François Patte
    Université Paris 5 - Paris

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