Understanding, shortcomings, and Gain XEN, OpenVZ and KVM

on this occasion I will try to discuss a little bit about the definition of the XEN, OpenVZ, KVM, hopefully can help users in the use of their VPS.

1. XenServer (XEN)Xen Server is a server virtualization platform from Citrix, to optimize Windows and Linux virtual servers, which all require the ability to create and manage a virtual infrastructure.

Xen is an open source virtual machine manager and monitor, developed at the University of Cambridge. Created with the goal to run up to one hundred and operating system features air-filled (full featured OSS) on only one computer. Paravirtualisasi using the Xen virtualization technology provides secure isolation, resource regulator, the warranty for quality-of-services and live migration of a virtual machine.

To run Xen, basic operating system must be modified specifically for its own needs and in this way to achieve very high performance virtualization without special hardware.

XenServer road directly on server hardware without requiring operating system.XenServer works on a simple element-element of physical Machine (such as hard drives, resources and ports) and allocate to virtual machines (VMs) that are running.XenCenter can manage XenServer hosts, pools and shared storage, and deploy, manage and monitor Virtual Machines on Windows Desktop Machine.

XEN (Called Virtual Dedicated Server)Advantages :a. The system stands alone like a Dedicated Serverb. Using the SWAP.c. Almost no problem with setting because it is not constrained by the node.d. If Memory Dedicated expires, the SWAP will function automatically and do not like OpenVZ are down, the XEN just cause VDSnya system will slow down.e. Can support the installation of Windows Server.

Deficiency :a. Setup Node with LVM partition (Since it takes for the client VDSnya VG).b. XEN only runs on 256 MB of RAM (under this specification will not be stable).c. Need more space in the node for temp process. 

2.  OpenVZ

OpenVZ is a virtualization at the level of the OS (Operating System) is based on a modified Linux kernel that allows a physical server to run multiple instances, called containers, virtual private server (VPS) or Virtual Environments (VE). The term is more commonly used is container. Container is often analogous to chroot or jail, but container is much better in terms of insulation, security, functionality, and Management of resources.OpenVZ consists of a special Linux kernel and some user-level tools. OpenVZ is very portable, do not rely on the support of VT on the CPU, so it is available for a number of types of CPUs including x86, x86-64, IA-64, PowerPC and SPARCVirtualization-OS is very different from the products virtualize hardware / machine like VMWare, VirtualBox, KVM, and Xen. In OpenVZ you can only make Linux virtualization on Linux.Why use OpenVZ?Because of the relatively mild, Virtualization-OS offers a number of advantages than-Hardware Virtualizationa. Much more efficientb. Allow more number of containers in a single server.c. Offer a resource management parameters more complete / detail.d. The resource management is dynamic, so no need to restart the container systemOpenVZ can achieve the performance, scalability and density are better because there is a Linux kernel running on a physical host in which each container is only taking resources needed to run the process / service in it alone, no need for the entire operating system. A basic-container can add 8-14 processes on the host. OpenVZ can also handle advanced applications such as multi-threaded Java applications.Another advantage of OpenVZ is offering a variety of dynamic resources management parameters include: the use of memory, number of processes, the level of CPU usage, disk space usage, etc. all of which can be changed-fox container while still running. OpenVZ also supports quota of disk space and disk space quotas for user / group within the container.VPS: OpenVZ Vs XENOpenVZ (Called Virtual Private Server)Advantages :a. Can enacted overselling.b. Setup is easier to remember linux partition used by default.c. Using Burst RAM.d. Management Server more easily than Xen.Deficiency :a. No support SWAP.b. All the VPS that is highly dependent on the node (Because of the kernel come to the Node).c. If the memory and Burst discharged dedicated / VPS will then stuck down.d. Some settings are limited by Node.e. Only supports Linux.

3. Kernel-Based Virtual Machine (KVM)

Kernel-Based Virtual Machine (KVM) is a virtualization technology (hypervisor) developed by Linux. KVM is a virtualization solution to perform on Linux with hardware type x86 (64-bit).KVM is implemented as a loadable kernel modules that transform the Linux kernel into a bare metal hypervisor. There are two main design principles adopted by the KVM with the aim to become a KVM hypervisor with high performance and surpass other open source hypervisors.- First, the team KVM apply the adage "do not reinvent the wheel". There are many components that are required by the KVM hypervisor that is able to virtualize the CPU and memory, such as memory regulator, process scheduler, I / O stack, device drivers, the safety regulator, network stack, and so on. In fact, a hypervisor is a special operating system, hypervisor purposes only differ with other general purpose operating system. Hypervisor running virtual machines, not applications. Because the Linux kernel already includes the core features required by the hypervisor and Linux has become a platform scale enterprise which is stable for more than fifteen years, KVM is built on the Linux kernel to make it more efficient, rather than writing all the required components such as regulating memory and scheduler from scratch.- Secondly, because KVM is designed after the emergence of assisted virtualization technology (hardware assisted virtualization), KVM does not need to implement the features that have been provided by the hardware. KVM requires Intel VT-x or AMD-V and use these features for CPU virtualization. Due to exploit hardware support already available, KVM hypervisor is able to design an optimal solution without requiring hardware support burden and unnecessary modifications to the guest operating system support.In this case, KVM learn from experience Xen. One major challenge is the Xen architecture domain0 solution architecture and the Xen hypervisor. Because Xen hypervisor provides a core platform features in the stack, Xen needs to implement features, such as scheduler and memory regulator, built from scratch. For example, when the Linux kernel has a regulator of memory that have been tested and both include support for NUMA and large-scale system, the Xen hypervisor needs to build support for this from the beginning. Similarly, features such as power management in Linux has matured and has been proven in the field should be implemented back on the Xen hypervisor.