Cloud Computing System: Citrix XenServer Virtualization Platform

Follow GigeNET on Twitter

Call Us Today: (800) 908-7115
Local Number: (224)-265-9165
Request a Call

Citrix XenServer


Brief Review of Virtualization

As covered in another article on Choosing a Server Virtualization Platform, virtualization allows an organization to make effective use of it's hardware resources. By pooling all its IT resources together, corporations can ensure that hardware is hardly ever underused.

With Server hardware being so expensive, it becomes even more important to ensure that it's utilized properly. What if you have a legacy application that only runs on a particular operating system? It doesn't make sense to buy a new server just for that one application. With virtualization, you can install several operating systems on a single server, thereby getting the maximum juice out of your hardware.

Another interesting use of virtualization is for testing purposes. You can take a risky application, and create the illusion that it's running on a new system of it's own. Such a program is running in what is called a sandbox, meaning that it can't do any real damage. Virtualization can also be used to simulate several computers running on a network.

The uses are many and the benefits of virtualization will only become clearer as time goes by.

Citrix XenServer

XenServer by Citrix is a virtualization platform. It is based on the Xen server which is open source. As such, it benefits a great deal from the contribution of those who are outside the company. For example, Intel and AMD have both contributed to it's development so that it can run on their special chips that support hypervisors.

Recently, Citrix started offering XenServer free. Customers who would like professional support need to purchase it. Compared to similar offerings by VMWare, it's significantly cheaper and cost effective. Citrix offers the ability to ugrade to what is called XenServer Essentials that further help customers manage their virtual systems.


XenServer which is based on Xen takes a similar approach to the organization Guest OSs. A Guest OS is the OS that is running on XenServer. Ideally, each guest OS should not know that it is not running on a bare metal device.

However, Xen requires that each OS be enlightened. This means that the operating system must understand that it is not running on bare metal server. This requirement requires each OS to be modified slightly. As of now, almost all modern operating systems can be "enlightened" using a simple patch. Vista SP1 supports enlightenment and so does XP SP3. In fact, even Ubuntu, which is an open source OS supports enlightenment.

However, it should be noted that there are certain processors which when used, do not require the OSs to be enlightened. These include AMD's "AMD V" processor and the "Intel VT" processor. You can run a guest OS unmodified using these chips.

Guest OS Support

XenServer runs a very wide range of operating systems. Linux based OSs in particular are extremely well supported as well as lots of other UNIX based operating systems such as Minix and a wide range of BSD based systems.

Windows can be run unmodified only with certain hardware as mentioned above. Xen is increasing it's ability to run Windows all the time. Vista and XP can be run in this manner.

Hardware Compatibility

When it comes to driver support, virtualization has always presented a unique problem. This is because hypervisors are not designed to implement all the wide range of devices that can be attached to a server, and yet it has to present the hardware to the Guest OSs. This has traditionally resulted in poor support and the hypervisors presenting only a subset of the actual range of devices present.

However, Xen works around this problem by elevating one of the Guest OSs to a level above the others. This GuestOS which will usually have all the necessary drivers will detect the devices and XenServer will then ensure that this support is migrated to the other OSs as well. This is a very elegant solution to what is otherwise a thorny problem.

Due to this technique, XenServer supports an unusually large number of devices. The primary GuestOS also known as the dom0 OS has already done all the hard work of supporting the hardware devices. Xen simply reuses this support to enable the other guests to use this support.

Management Tools

Management tools are critical to the smooth deployment of any virtualization solution. There are two aspects to the management tools - Xen and XenServer. Since Xen is open source, there are a large number of applications that can be used to manage the systems. However, these are mostly free and are not supported commercially.

For large enterprises, support is a key factor, and Citrix provides the XenServer Essentials tool set for advanced management capabilities with its free XenServer software.

XenServer Essentials provides a large number of powerful management tools for enterprises that enable it to more efficiently manage it's hardware and software. Two of these benefits are given below:

StorageLink Technology

The StorageLink Technology included in XenServer Essentials allows XenServer to use existing storage systems seamlessly. The best part is the ease of use - StorageLink allows one click access to third party storage services and allows an easy setup of different types of storage configuration. Without this, you would need to use different proprietary functionalities with a large amount of overlap - reducing the efficiency of the system and eating up resources.

Storage providers have several different way of providing storage solutions to enterprises. These various techniques provide different solutions to the various problems of backup, synchronization and availability that corporations face. Since the solutions work on a very low level, there is the danger that the virtualized systems will not be able to make use of the systems since XenServer isn't the OS that these systems were built for.

StorageLink allows companies to participate in Citrix's "Open Storage Program" that ensures that XenServer will be able to provide the GuestOSs with seamless access to these technologies. The Open Storage Program also ensures interoperability with Microsoft's Hyper-V virtualization platform which is a welcome bonus.

This support ensures that XenServer can provide efficient functionality and features to the Guest OSs thereby improving it's viability as a virtualization platform.

Automated Lab Management

Virtualization is often used for a process known as "Lab Management." Companies dealing with software have to often test, and demonstrate their software to clients. For regular and local applications, this isn't an issue but for complex enterprise applications, it can be very time consuming.

Large applications usually span several servers and network configurations. You might have an Oracle database, a large number of clients running multiple OSs, a web server and a file server. An application that utilizes all these resources needs to be tested thoroughly before going production. In addition, when such a system needs to be shown to a client, it's impossible to create the conditions necessary to test it in reality.

This is where virtualization comes in. Using a virtualization software like XenServer, you can create multiple test machines and servers on a single piece of hardware, with each OS thinking that it's an independent entity. You can then create virtual network connections between the machines with the specified configurations and test or demonstrate the application on that configuration.

However, even this is time consuming. And that is where Automated Lab Management from Citrix XenServer Essentials comes in. Automated Lab Management allows administrators to create and "save" such configurations so that they can be recreated at any time with the click of a button. Such procedures are less prone to errors as the manual component of setting them up is taken out. It only needs to be done once.

In addition, several such configurations and setups can be maintained, allowing Quality testers to reuse them easily and effectively. The end result is increased productivity and lower overall cost as well as improved productivity.


Since XenServer is free to the public, there is no formalized support out of the box. For casual users, the Citrix forums are a great place to ask questions and get information. However, for businesses, this is not enough.

Citrix allows customers to purchase separate support packages that allow business users to receive professional support for their installations. There are many such Tech Support Programs from Citrix - a few of them are shown below:

* Preferred XenServer & Citrix Essentials - 5 incidents are allowed with XenServer or Citrix Essentials Products within regular business hours
* Preferred XenServer & Citrix Essentials Extend - The same as above, but with 24x7 support and 4 named contacts instead of 2
* Preferred 25: 25 Incidents with invitations to annual training events as well as a Support account manager - All Citrix products supported

As you can see, there are several packages to choose from and each business will have a different requirement. The Citrix support site has more details.

Also, along with a purchase of XenServer essentials, customers receive 1 year of the "Subscription Advantage" program which includes version upgrades.

XenServer and Gigenet

GigeNET allows users to easily install XenServer onto their systems and provides easy management of Operating Systems on it. When you sign up for one of our servers, you can not only customize what hardware you would like it to run, you can also choose which Virtualization system you would like to put onto it.

This easy configuration and management makes GigeNET an exceptionally powerful solution for your business needs. We understand that for your business, time is of the essence and we make no compromise on fast and reliable delivery. To start, order your server directly from GigeNET now.

Have a Question or Need Help?

Features at a Glance

  • Redundant Locations - LA Cloud Servers and Chicago Cloud Servers now available!
  • Fully Redundant, Self Healing SAN's CPU utilization based on the amount memory assigned to a machine.
  • Xen Hypervisor using Citrix Xenserver Technology.
  • A friendly, reliable control panel that offers usability second to none.
  • Multiple elastic public IP addresses.
  • Support for multiple linux distributions.
  • No reselling or over commission of resources.
  • Direct KVM console access that can be used to recover a file system failure or malformed network configuration.
  • Completely transparent private networking with free unmetered bandwidth.
  • All cloud nodes are based on 64-bit architectures.
  • Ability for Virtual Machines to use 32-bit or 64-bit architectures.
  • Full Windows Server 2003 and 2008 Support for all Cloud Servers!

Cloud Products

Keep up to date with Cloud Computing

Drop1 Button1 BG1 BG2 BG3