The Never Ending Story of Xen and Linux
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What is it about Xen and Linux? First, let’s define the terms. Xen is actually a virtualization technology for the Linux kernel that allows you to try out new upgrades. Running Xen happens in a virtual environment where the actual system is simulated without having to bother the original system.
Xen is installed into Linux using a driver called the Fedora Core. The moment the driver is installed, Xen operates the same way on all sorts of distribution. Virtualization in Linux is possible with a “sandbox” that can test new software and operate several virtual machines on the very same Linux box. Xen, a paravirtualizing VMM (Virtual Machine Monitor) is one of those “sandboxes” that was developed at the University of Cambridge.
With Xen, the operating system (OS) is modified in some areas in order to make calls right into the hypervisor and the application running remain unmodified. Since Xen needs the OS to be modified, there is a need to port the hypervisor to the Xen architecture because an existing Linux kernel cannot just operate it in the Xen hypervisor.
Users have been trying to view the Xen-Linux partnership in virtualization. One user thinks that the idea of integrating Xen into the kernel to ease up the development is not such a good idea. A better idea would be is to make paravirtualization from Xen available only to Linux. Xen makes it possible to use older hardware for virtualization to take place. But if PVM is removed from Xen, this capability is likewise removed.
The virtualization process should be done in the hardware. It is not true that virtualization is more superior than paravirtualization. The hack, HVM, was brought into the picture to run operating systems that are not modified in a VM without having to do run-time binary translation such as VMware. It is more efficient to leave the skewed scales that does compute-intensive load in a VM during times when modified drivers are used for the operating system of the paravirtualized hardware. Virtualization of hardware is done more efficiently with unmodified operating systems but it doesn’t really mean that it is the most efficient method.
Another user thinks that Linux supports the device driver better than FreeBSD or Solaris. He says that the driver is not the issue in server space. All servers have the same components like those Intel networking chips or the Nvidia chipsets. Hard disk controllers are either provided by Adaptec or LSI. In virtualization, it is not necessarily more advantageous to have more drivers for more advanced or for older hardware.
What really matters in paravirtualization is fault management and anticipation architecture. One way of doing sparse provision on virtual disks is to lower the consumption of the disk. These things cannot be found in Linux and they are vital in doing virtualization even with one or two VMs.
Major promoters and the media regularly talk about Linux developers being the best and most innovative. The truth ism Linux just moves around the inventions of Xen in the past years. The integration being talked about in the beginning of this write-up has not moved anything forward. By that time, NetBSD and OpenSolaris have integrated into their operating systems. Therefore, the problem is not in the code that cannot be integrated or other technical difficulties because coding guidelines and processes are very rigorous in OpenSolaris. It is possible that it’s just the NIH having its own virtualization layer with KVM.
The ending of the story relies on the fact that even with Linux destroys the Xen implementation, there are operating systems available that can take its place. And one of it is OpenSolaris.