Virtualization concepts in cloud computing

Unit 3 Virtualization concepts in Cloud Computing By Dr Mohammad Zunnun Khan

Virtualization in Cloud Computing  Virtualization is the "creation of a virtual (rather than actual) version of something, such as a server, a desktop, a storage device, an operating system or network resources".  In other words, Virtualization is a technique, which allows to share a single physical instance of a resource or an application among multiple customers and organizations.  It does by assigning a logical name to a physical storage and providing a pointer to that physical resource when demanded.

Basic Concept of Virtualization  Creation of a virtual machine over existing operating system and hardware is known as Hardware Virtualization.  A Virtual machine provides an environment that is logically separated from the underlying hardware.  Concept is not new. Multi Programming – Each Process thinks it has complete control on all of the resources. ◦ Virtual Memory ◦ CPU Sharing

Similarities and Differences with Multiprogramming  Multi Programming ◦ CPU is shared among processes ◦ Memory is shared using Page Tables. ◦ Process knows it is being managed- uses system calls.  Virtualization ◦ CPU is shared among OSs. ◦ Memory is shared using more level of indirections. Multiple Page tables. ◦ OS may or may not know that it is being managed.

Virtualization Architecture  OS assumes complete control of the underlying hardware.  Virtualization architecture provides this illusion through a hypervisor/VMM.  Hypervisor/VMM is a software layer which: ◦ Allows multiple Guest OS (Virtual Machines) to run simultaneously on a single physical host ◦ Provides hardware abstraction to the running Guest OSs and efficiently multiplexes underlying hardware resources.

Physical vs. Virtual Machine image source: vmware.com

Physical  Single OS  H/W + S/W tightly coupled  Application crashes affect all  Resource under-utilization Virtual Machine  Machine view to OS is independent of hardware  Multiple OS (isolated apps)  Safely multiplex resources across VMs

Types of Virtualization  There are two main parts of machine ◦ Host Machine, on which the virtual machine is going to create ◦ Guest Machine, on which user is going to use virtual service.  There are mainly 4 types of virtualization ◦ Hardware Virtualization. ◦ Operating system Virtualization. ◦ Server Virtualization. ◦ Storage Virtualization.

Hardware Virtualization:  When the virtual machine software or virtual machine manager (VMM) is directly installed on the hardware system is known as hardware virtualization.  The main job of hypervisor is to control and monitoring the processor, memory and other hardware resources.  After virtualization of hardware system we can install different operating system on it and run different applications on those OS.

 Usage:  Hardware virtualization is mainly done for the server platforms, because controlling virtual machines is much easier than controlling a physical server.

Operating System Virtualization  When the virtual machine software or virtual machine manager (VMM) is installed on the Host operating system instead of directly on the hardware system is known as operating system virtualization.  Usage:  Operating System Virtualization is mainly used for testing the applications on different platforms of OS.

Server Virtualization:  When the virtual machine software or virtual machine manager (VMM) is directly installed on the Server system is known as server virtualization.  Usage:  Server virtualization is done because a single physical server can be divided into multiple servers on the demand basis and for balancing the load.

Storage Virtualization:  Storage virtualization is the process of grouping the physical storage from multiple network storage devices so that it looks like a single storage device.  Storage virtualization is also implemented by using software applications.  Usage:  Storage virtualization is mainly done for back-up and recovery purposes.

What is Hypervisor  If you know what a private cloud is and you know the infrastructure of it, you’ve probably heard about hypervisor.  It is the part of the private cloud that manages the virtual machines, i.e. it is the part (program) that enables multiple operating systems to share the same hardware.  Each operating system could use all the hardware (processor, memory) if no other operating system is on. That is the maximum hardware available to one operating system in the cloud.  Nevertheless, the hypervisor is what controls and allocates what portion of hardware resources each operating system should get, in order every one o them to get what they need and not to disrupt each other.

Types of Hypervisor  There are two types of hypervisors  Type 1 hypervisor: hypervisors run directly on the system hardware – A “bare metal” embedded hypervisor,  Type 2 hypervisor: hypervisors run on a host operating system that provides virtualization services, such as I/O device support and memory management.

Type 1 hypervisors: 1. VMware ESX and ESXi  These hypervisors offer advanced features and scalability, but require licensing, so the costs are higher.  There are some lower-cost bundles that VMware offers and they can make hypervisor technology more affordable for small infrastructures.  VMware is the leader in the Type-1 hypervisors. Their vSphere/ESXi product is available in a free edition and 5 commercial editions. 2. Microsoft Hyper-V  The Microsoft hypervisor, Hyper-V doesn’t offer many of the advanced features that VMware’s products provide. However, with XenServer and vSphere, Hyper-V is one of the top 3 Type-1 hypervisors.  It was first released with Windows Server, but now Hyper-V has been greatly enhanced with Windows Server 2012 Hyper-V. Hyper-V is available in both a free edition (with no GUI and no virtualization rights) and 4 commercial editions – Foundations (OEM only), Essentials, Standard, and Datacenter. Hyper-V

3. Citrix XenServer  It began as an open source project. The core hypervisor technology is free, but like VMware’s free ESXi, it has almost no advanced features. Xen is a type-1 bare-metal hypervisor. Just as Red Hat Enterprise Virtualization uses KVM, Citrix uses Xen in the commercial XenServer.  Today, the Xen open source projects and community are at Xen.org. Today, XenServer is a commercial type-1 hypervisor solution from Citrix, offered in 4 editions. Confusingly, Citrix has also branded their other proprietary solutions like XenApp and XenDesktop with the Xen name. 4. Oracle VM  The Oracle hypervisor is based on the open source Xen. However, if you need hypervisor support and product updates, it will cost you. Oracle VM lacks many of the advanced features found in other bare-metal virtualization hypervisors.

Type 2 hypervisor 1. VMware Workstation/Fusion/Player  VMware Player is a free virtualization hypervisor.  It is intended to run only one virtual machine (VM) and does not allow creating VMs. VMware Workstation is a more robust hypervisor with some advanced features, such as record-and-replay and VM snapshot support.  VMware Workstation has three major use cases:  for running multiple different operating systems or versions of one OS on one desktop,  for developers that need sandbox environments and snapshots, or  for labs and demonstration purposes. 2. VMware Server  VMware Server is a free, hosted virtualization hypervisor that’s very similar to the VMware Workstation. VMware has halted development on Server since 2009 3. Microsoft Virtual PC  This is the latest Microsoft’s version of this hypervisor technology, Windows Virtual PC and runs only on Windows 7 and supports only Windows operating systems running on it.

4. Oracle VM VirtualBox  VirtualBox hypervisor technology provides reasonable performance and features if you want to virtualize on a budget. Despite being a free, hosted product with a very small footprint, VirtualBox shares many features with VMware vSphere and Microsoft Hyper-V. 5. Red Hat Enterprise Virtualization  Red Hat’s Kernel-based Virtual Machine (KVM) has qualities of both a hosted and a bare- metal virtualization hypervisor. It can turn the Linux kernel itself into a hypervisor so the VMs have direct access to the physical hardware.

KVM  This is a virtualization infrastructure for the Linux kernel. It supports native virtualization on processors with hardware virtualization extensions.  The open-source KVM (or Kernel-Based Virtual Machine) is a Linux-based type-1 hypervisor that can be added to most Linux operating systems including Ubuntu, Debian, SUSE, and Red Hat Enterprise Linux, but also Solaris, and Windows.  .

Benefits of using Virtual Machines  Instant provisioning - fast scalability  Live Migration is possible  Load balancing and consolidation in a Data Center is possible.  Low downtime for maintenance  Virtual hardware supports legacy operating systems efficiently  Security and fault isolation

Load Balancing Better Response time

 Consolidation - Reduces number of Physical Machine req uirement

References  Amburst et al. “Above the Clouds: A Berkeley view of cloud computing”  David Chisnall. “The Definitive Guide to XEN Hypervisor”.  Prof. Purushottam Kulkarni, CSE, IITB, His Presentation.  Vmware “ www.vmware.com”  Wikipedia and Internet.

 Thank You  Any Questions? Email me on zunnunkhan@gmail.com

Virtualization concepts in cloud computing

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