I’ve already written about creating a partition size larger than 2TB under Linux using GNU parted command with GPT. In this tutorial, I will provide instructions for booting to a flat 2TB or larger RAID array under Linux using the GRUB boot loader.
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Recently my friend emailed me an interesting scenario. He installed FreeBSD 6.0 / 7.0 in the first primary partition (10G). One day he installed Ubuntu Linux. He can boot into Linux but not able to boot into FreeBSD. Now, my friend wanted to boot both FreeBSD and Ubuntu Linux via Grub boot loader.
It is not that hard to configure grub to boot FreeBSD. You just need to add following three lines to grub configuration file (/boot/grub/menu.lst). Boot into Ubuntu Linux and use text editor to edit the file /boot/grub/menu.lst ( Red hat and friends [ Fedora / CentOS ] try /etc/grub.conf file) :
$ gksudo gedit /boot/grub/menu.lst
$ gksudo vi /boot/grub/menu.lst
Append FreeBSD boot Configuration:
title FreeBSD 7.0 root (hd0,a) kernel /boot/loader
Save and close the file. To see changes or to boot into FreeBSD reboot Ubuntu Linux box.
- title FreeBSD 7.0 : Start a new boot entry. User always sees this title and hit enter key to boot os.
- root (hd0,a) : Actual part is to select the correct root partition. The root option set the current root device to the device, then attempt to mount it to get the partition size. In above example – hd0 is your first hard disk i.e. hda in Linux. In grub hda is hd0. Likewise your first, second partition on the first hard disk â€“ hda1, hda2, becomes hd0,0 hd0,1 in Grub. In short, you are asking to use first hard first partition (remember FreeBSD use a,b,c names to represent partition names). If you have installed FreeBSD on third partition then you need to use following root statement:
- kernel /boot/loader : Use to load the primary boot image. FreeBSD use /boot/loader to load rest of kernel and os.
You can set a password for the GRUB bootloader. This prevents users from entering single user mode or changing settings at boot time.
When your system is rebooted, grub presents the boot option menu. From this menu one can easily login into a single user mode without the password which might result into compromise system security.
For example, anyone can access the data or change the settings. However you can setup a password for grub with password option. This option forces grub to ask for a password before making any changes or entering into single user mode. You need to type p followed by password.
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