My First Experience with GRUB

Hi Friends. So, here I am again there with my experience and I think my GRUB experience (till now) would be an amazing topic

So let us start from the start 🙂

What is GRUB ?

GRUB is a boot loader designed to boot a wide range of operating systems from a wide range of file systems. (copied :-p)

GRUB creates and manages the screen containing list of OS available in the system that we see while booting process. (in simple language)

Why I felt the need to change GRUB boot loader?

1. To make the boot menu visible

When Xen hypervisor is installed in Ubuntu 14.04 or higher versions it automatically changes the GRUB to boot XEN and hides the OS list menu on boot. So, if you want the menu to appear on boot then follow the steps :

Open /etc/default/grub and change GRUB_HIDDEN_TIMEOUT

GRUB_HIDDEN_TIMEOUT=-1

And then update your grub by running the following command

update-grub2

and on next boot you will see the boot menu 🙂

2. To pass boot parameters to Xen

I have to change the scheduler in Xen to credit2 scheduler and for that I have to pass the parameters to Xen kernel.

Open /etc/default/grub and append the following line at the end

GRUB_CMDLINE_XEN=”sched=credit2″

And update your grub

update-grub2

So to pass parameters to Xen Kernel you just have to insert parameters between ” ”

Example

GRUB_CMDLINE_XEN=”sched=credit2  cpuinfo=1″

grub

But this is not an end I will keep updating about GRUB. 🙂

Ubuntu 14.04 with Xen and Virtual Machine Manager

Installation of Xen Hypervisor and Virtual Manager on Ubuntu 14.04.1

1. Install Ubuntu 14.04.1 and more importantly enable virtualization in boot options
You can get the installation steps from Ubuntu official site.

2. Open terminal and install xen hypervisor
sudo apt-get install xen-hypervisor-amd64
(installing 64 bit hypervisor runs on 32 bit dom0 and also creates 64 bit domU)

Then reboot (you don’t have to update grub)
sudo reboot

3. After rebooting just to check if Xen booted with Linux
sudo xl info

sudo apt-get install bridge-utils

4. Open  /etc/network/interfaces and change it

auto lo
iface lo inet loopback

auto xenbr0
iface xenbr0 inet dhcp
    bridge_ports eth0

auto eth0
iface eth0 inet manual

Then restart network manager
sudo ifdown eth0 && sudo ifup xenbr0 && sudo ifup eth0

5. Now install Virtual Machine Manager
sudo apt-get install virt-manager

Now restart your system open virtual machine manager and add connection Xen.
Then start creating your domU’s.

Help for more OS at : https://help.ubuntu.com/community/Xen