Grant McWilliams

A lot of this tutorial was stolen from the CentOS wiki - http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU. I've shortened it by quite a bit to make it easier.  I assume you know this already but you will need to be logged in as root or have root privileges in order to execute this tutorial.

Creating an Image

The first step is to create an image that will hold the domU virtual disk. Since this can just be a file filled with zeros, our usual friend dd comes in handy.  The following command will create a /srv/xen/centos5.img file of 11GB, although the actual data blocks are allocated in a lazy fashion meaning that the disk image doesn't actually take up the whole 11GB until you fill it up. This is referred to as a sparse file.

dd if=/dev/zero of=/srv/xen/centos5.img oflag=direct bs=1M seek=10240 count=1

Preparing the Xen configuration file for installation

Xen uses one configuration file per domain. The configuration for the domain will be slightly different during the installation, because we have to provide installation kernels, and possibly some boot parameters. Here we download the installation kernel, ramdisk and xen config file.

A lot of this tutorial was stolen from the CentOS wiki - http://wiki.centos.org/HowTos/Xen/InstallingCentOSDomU. I've shortened it by quite a bit to make it easier.  I assume you know this already but you will need to be logged in as root or have root privileges in order to execute this tutorial.

Creating an Image

The first step is to create an image that will hold the domU virtual disk. Since this can just be a file filled with zeros, our usual friend dd comes in handy.  The following command will create a /srv/xen/centos5.img file of 11GB, although the actual data blocks are allocated in a lazy fashion meaning that the disk image doesn't actually take up the whole 11GB until you fill it up. This is referred to as a sparse file.

dd if=/dev/zero of=/srv/xen/centos5.img oflag=direct bs=1M seek=10240 count=1

Introduction

A lot of this tutorial was stolen from my CentOS 5 Installation which in turn was stolen from the CentOS wiki. I've shortened and updated it for installing a CentOS 6 DomU. I just copy and paste all the indented lines into a root terminal and voila! a CentOS VM.

1. Creating an Virtual Disk Image

The first step is to create an disk image that will act as the VM hard drive. The following command will create a 4 GB sparse disk image named /srv/xen/centos6.img. A sparse file is created in such a way that the disk image doesn't actually take up the whole 4GB until you fill it up. If you'd like a larger (11GB) disk image substitute seek=10240 into the following line. I make my VMs nice and small so I can move them around easier. Making a disk image larger or adding a second drive later is easier than making it smaller or taking a drive away.

dd if=/dev/zero of=/srv/xen/centos6.img oflag=direct bs=1M seek=3800 count=1

wget http://mirror.centos.org/centos/6/os/i386/isolinux/vmlinuz -O /boot/vmlinuz-xen6-install
wget http://mirror.centos.org/centos/6/os/i386/isolinux/initrd.img -O /boot/initrd-xen6-install
wget http://www.grantmcwilliams.com/files/centos6-install -O /etc/xen/centos6

3. Starting the installation

A kickstart file holds instructions for automatic installation and is referenced in my xen config above. My example kickstart file is very minimal but is enough to get a working CentOS 6 VM.

Introduction

A lot of this tutorial was stolen from my CentOS 5 Installation which in turn was stolen from the CentOS wiki. I've shortened and updated it for installing a CentOS 6 DomU. I just copy and paste all the indented lines into a root terminal and voila! a CentOS VM.

1. Creating an Virtual Disk Image

The first step is to create an disk image that will act as the VM hard drive. The following command will create a 4 GB sparse disk image named /srv/xen/centos6.img. A sparse file is created in such a way that the disk image doesn't actually take up the whole 4GB until you fill it up. If you'd like a larger (11GB) disk image substitute seek=10240 into the following line. I make my VMs nice and small so I can move them around easier. Making a disk image larger or adding a second drive later is easier than making it smaller or taking a drive away.

dd if=/dev/zero of=/srv/xen/centos6.img oflag=direct bs=1M seek=3800 count=1

wget http://mirror.centos.org/centos/6/os/x86_64/isolinux/vmlinuz -O /boot/vmlinuz-xen6-install
wget http://mirror.centos.org/centos/6/os/x86_64/isolinux/initrd.img -O /boot/initrd-xen6-install
wget http://www.grantmcwilliams.com/files/centos6_64-install -O /etc/xen/centos6

3. Starting the installation

A kickstart file holds instructions for automatic installation and is referenced in my xen config above. My example kickstart file is very minimal but is enough to get a working CentOS 6 VM.

Install Type

• Non-interactive
• Network boot
• Commandline

Introduction

This tutorial was written in the spirit of my CentOS 6 virtual machine (32 bit) installation on Xen howto which was based on the CentOS 5 version of the same. In those tutorials I created a disk, downloaded a kernel, kickstart file plus a xen config file which installed CentOS using the kickstart file. This has proven very popular since you can't install a paravirtualized domain using an install disk. This has been a very nice installation howto because you don't have to download any install CD/DVDs and you could create VMs using nothing more than a commandline login. It's also very nice because it can be mirrored locally if you're doing a bunch of them just by rsyncing a CentOS mirror locally then downloading my files and editing them.

I've recently migrated a lot of my XEN systems to Xen Cloud Platform and it's a very different animal indeed. However, I still needed a system of creating CentOS Virtual Machines in that same manner. I didn't want to download a CentOS install DVD or need a graphical login to install the OS thus this tutorial was born.

It uses the very same CentOS 6 kickstart file from my site as the Xen tutorial. It also uses the very same CentOS 6 repositories on the Internet so in a lot aspects it IS the same tutorial crafted for XCP but will be a bit shorter.

 More after the jump.

Install Type

• Non-interactive
• Network boot
• Commandline

Introduction

This tutorial was written in the spirit of my CentOS 6 virtual machine (64 bit) installation on Xen howto which was based on the CentOS 5 version of the same. In those tutorials I created a disk, downloaded a kernel, kickstart file plus a xen config file which installed CentOS using the kickstart file. This has proven very popular since you can't install a paravirtualized domain using an install disk. This has been a very nice installation howto because you don't have to download any install CD/DVDs and you could create VMs using nothing more than a commandline login. It's also very nice because it can be mirrored locally if you're doing a bunch of them just by rsyncing a CentOS mirror locally then downloading my files and editing them.

I've recently migrated a lot of my XEN systems to Xen Cloud Platform and it's a very different animal indeed. However, I still needed a system of creating CentOS Virtual Machines in that same manner. I didn't want to download a CentOS install DVD or need a graphical login to install the OS thus this tutorial was born.

It uses the very same CentOS 6 kickstart file from my site as the Xen tutorial. It also uses the very same CentOS 6 repositories on the Internet so in a lot aspects it IS the same tutorial crafted for XCP but will be a bit shorter.

To convert a QEMU qcow format disk to VirtualBox vdi format you need to have Qemu installed. Qemu has tools to help convert disk formats.

grant@workstation:~$ qemu-img convert hda-qcow.img -O raw hda.img

grant@workstation:~$ VBoxManage convertdd hda.img hda.vdi
VirtualBox Command Line Management Interface Version 1.6.0
(C) 2005-2008 Sun Microsystems, Inc.
All rights reserved.

Converting VDI: from DD image file="hda.img" to file="hda.vdi"...
Creating fixed image with size 1024966656 bytes (978MB)...

This will convert a QEMU qcow format disk image to VirtualBox vdi format.

If you're moving from a real server installation to a VirtualBox virtualized configuration you may want to take your real physical disk and just turn it into a virtual disk. There are advantages to creating a new disk and rsyncing your OS into it but this tutorial will show you how to make an exact copy of it. Note the exact copy will be the same size as the real physical disk so make sure you have enough drive space. This is most useful for Operating System images with shared storage for data. I wouldn't advise anyone to make a 1TB copy of their new drive and turn it into a VDI file!

To get the image from the disk use the dd command.

1. dd if=/dev/hda of=./hda.img
2. VBoxManage convertdd hda.img hda.vdi

grant@workstation:~$ dd if=/dev/hda of=./hda.img

grant@workstation:~$ VBoxManage convertdd hda.img hda.vdi
VirtualBox Command Line Management Interface Version 1.6.0
(C) 2005-2008 Sun Microsystems, Inc.
All rights reserved.

Converting VDI: from DD image file="hda.img" to file="hda.vdi"...
Creating fixed image with size 1024966656 bytes (978MB)...

This will make an exact copy of /dev/hda to the raw image file hda.img. Then VBoxManage will convert the raw disk hda.img to hda.vdi for use with VirtualBox.

If you're moving from a real server installation to a VirtualBox virtualized configuration you may want to take your real physical disk and just turn it into a virtual disk. There are advantages to creating a new disk and rsyncing your OS into it but this tutorial will show you how to make an exact copy of it. Note the exact copy will be the same size as the real physical disk so make sure you have enough drive space. This is most useful for Operating System images with shared storage for data. I wouldn't advise anyone to make a 1TB copy of their new drive and turn it into a VDI file!

To get the image from the disk use the dd command.

1. dd if=/dev/hda of=./hda.img
2. VBoxManage convertdd hda.img hda.vdi

grant@workstation:~$ dd if=/dev/hda of=./hda.img

grant@workstation:~$ VBoxManage convertdd hda.img hda.vdi
VirtualBox Command Line Management Interface Version 1.6.0
(C) 2005-2008 Sun Microsystems, Inc.
All rights reserved.

Converting VDI: from DD image file="hda.img" to file="hda.vdi"...
Creating fixed image with size 1024966656 bytes (978MB)...

This will make an exact copy of /dev/hda to the raw image file hda.img. Then VBoxManage will convert the raw disk hda.img to hda.vdi for use with VirtualBox.

How to move from a tap:aio file to an LVM Logical Volume.

In Xen we can provide virtualized hard drives several different ways. It's not uncommon to create a large empty file using dd and then specify it as the hard drive like this.