Not too long ago, one of my LinkedIn contacts, Mohsen Mostafa Jokar, wrote a book about Xen which is called “Hello Xen Project”. Mohsen is a Linux administrator who works at the newspaper Hamshahri as a network and virtualization administrator. His interest in virtualization goes back to when he was at school and saw a Microsoft Virtual PC for the first time. He installed it on a PC with 256 MB of RAM and used it to virtualize Windows 98 and DOS.
In addition to his fascination with virtualization, Mohsen is a translator and an author. He has translated and written books for IT beginners and professional users that focus on virtualization, security and Linux. A few books that he has worked on as a technical reviewer include “Elixir in Action,” “Learn Git in a Month of Lunches,” “Mesos in Action” and “Reverse Engineering for Beginners”.
Beyond Xen and the different Linux distributions and projects such as openSUSE, SUSE Linux Enterprise, Fedora, Knoppix, Red Hat and others, Mohsen is also familiar with virtualization technologies such as Qemu, Citrix XenServer and VMWare ESXi.
Mohsen’s Xen guide targets mainly virtualization beginners, and is available for free from the Xen Project Wiki page. He made it freely available by purpose: his intention is to get contributions from other experts to the documentation, to make Xen easier to understand, and encourage newbies to use Xen as their first choice virtualization platform.
In chapter one, Mohsen provides a brief history of virtualization. Of course the chapter does not go into deep details, but it explains what virtualization in IT generally means, why and when it should be used, which types of virtualization are available, and what the prevalent Open Source Linux virtualization tools currently are.
Chapter two focuses on the Xen project and how to install the software. The Xen Project hypervisor is a so-called “open-source type-1” or bare metal hypervisor, which makes it possible to run many instances of an operating system or different operating systems in parallel on a single machine. The Xen Project hypervisor is the only type-1 hypervisor currently available as open source. It is used as the basis for a number of different commercial and open source applications, such as: server virtualization, Infrastructure as a Service (IaaS), desktop virtualization, security applications, embedded and hardware appliances. At a high level, this chapter also covers the main components of the Xen Project components which are the hypervisor or Virtual Machine Monitor, Domain0 (Dom0) and DomainU (DomU). What’s more, for your convenience it lists the most important Xen commands.
The third Chapter contains a more detailed explanation of the managing or controlling Dom0 which includes the Host OS, the Xen daemon and a modified version of Qemu, and the virtual machine guest DomU, which consists of Virtual Disk, Network Devices and other Hardware plus the Virtual Machine configuration files. It also provides instructions on how to install and use the bootloader Grub.
Chapter four is all about using your Xen implementation now. It explains how to set up, run and manage your Virtual Machines. This includes how to configure DomU and set up your Network and Storage, which Linux tools to use to manage LVM and create your partitions, and how to monitor your Xen implementation.
Finally, in chapter five, which he named “Have fun with the Xen Project”, Mohsen shares some tips, tricks and troubleshooting information. This concluding chapter covers a bunch of additional topics, from converting a VirtualBox VM to Xen, using SELinux with Xen, setting up and managing a Citrix XenServer, to recovering a corrupted VM and monitoring your virtual environment with Nagios.
Call for Contribution
Mohsen shares his book in the true sense of open source. He hopes that more Xen users and experts will contribute their knowledge about and expertise with Xen as a stable and reliable virtualization platform. And contribution is really easy via this Wiki page.
Thus – if you want to help to improve this guide, by editing the existing content, casting an earnest eye over proper phrasing, adding information and know-how from your own experiences, or by any other idea you might have – just contact Mohsen at firstname.lastname@example.org and let him know how you would like to contribute.