Cloud Computing: Virtualization
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- Virtualization allows multiple operating systems to run concurrently on a single physical machine by presenting each virtual operating system with a virtual hardware environment. A hypervisor manages access to the physical hardware resources and isolates the virtual machines. - Cloud computing extends virtualization by allowing virtual servers and other resources to be dynamically provisioned on demand from large shared computing infrastructure. This improves flexibility and allows users to pay only for resources that are consumed. - The hypervisor software manages the virtual machines and allocates physical resources to each one while isolating them from each other. Example hypervisors include VMware, Xen, and KVM. Virtualization improves hardware utilization and makes infrastructure more flexible and cost-effective.
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Cloud Computing: Virtualization
- 1. Dr. Neeraj Kumar Pandey Virtualization and Cloud Computing
- 2. Definition Dr. Neeraj Kumar Pandey Virtualization is the ability to run multiple operating systems on a single physical system and share the underlying hardware resources. It is the process by which one computer hosts the appearance of many computers. Virtualization is used to improve IT throughput and costs by using physical resources as a pool from which virtual resources can be allocated.
- 3. Virtualization Architecture Dr. Neeraj Kumar Pandey •A Virtual machine (VM) is an isolated runtime environment (guest OS and applications) •Multiple virtual systems (VMs) can run on a single physical system
- 4. Benefits of Virtualization Dr. Neeraj Kumar Pandey Sharing of resources helps cost reduction Isolation: Virtual machines are isolated from each other as if they are physically separated Encapsulation: Virtual machines encapsulate a complete computing environment Hardware Independence: Virtual machines run independently of underlying hardware Portability: Virtual machines can be migrated between different hosts.
- 5. Virtualization in Cloud Computing Dr. Neeraj Kumar Pandey Cloud computing takes virtualization one step further: You don’t need to own the hardware Resources are rented as needed from a cloud Various providers allow creating virtual servers: Choose the OS and software each instance will have The chosen OS will run on a large server farm Can instantiate more virtual servers or shut down existing ones within minutes You get billed only for what you used
- 6. Hypervisor Dr. Neeraj Kumar Pandey A hypervisor, a virtual machine manager/monitor (VMM), or virtualization manager, is a program that allows multiple operating systems to share a single hardware host. Each guest operating system appears to have the host's processor, memory, and other resources all to itself. However, the hypervisor is actually controlling the host processor and resources, allocating what is needed to each operating system in turn and making sure that the guest operating systems (called virtual machines) cannot disrupt each other.
- 7. • Hypervisor plays an important role in the virtualization scenario by virtualization of hardware. It provides support for running multiple operating systems concurrently in virtual servers created within a physical server. • The virtualization layer is the software responsible for hosting and managing all VMs. The virtualization layer is a hypervisor running directly on the hardware. • Example: VMWare, Xen, KVM. hypervisor Dr. Neeraj Kumar Pandey
- 8. Hardware CPU Memory NIC DISK • Only one OS can run at a time within a server. • Under utilization of resources. • Inflexible and costly infrastructure. • Hardware changes require manual effort and access to the physical server. Operating System Multiple Software Applications Server without virtualization Dr. Neeraj Kumar Pandey
- 9. Hardware CPU Memory NIC DISK Hypervisor • Can run multiple OS simultaneously. • Each OS can have different hardware configuration. • Efficient utilization of hardware resources. • Each virtual machine is independent. • Save electricity, initial cost to buy servers, space etc. • Easy to manage and monitor virtual machines centrally. Virtual Server 1 Operating System Multiple Software Applications Virtual Server 2 Operating System Multiple Software Applications Server with virtualization Dr. Neeraj Kumar Pandey
- 10. Full virtualization • Enables hypervisors to run an unmodified guest operating system (e.g. Windows 2003 or XP). • Guest OS is not aware that it is being virtualized. • E.g.: VMware uses a combination of direct execution and binary translation techniques to achieve full virtualization of server systems. Hardware CPU Memory NIC DISK Hypervisor Virtual Server 1 Operating System Multiple Software Applications Virtual Server 2 Operating System Multiple Software Applications HYPERVISOR TYPE Dr. Neeraj Kumar Pandey
- 11. Para virtualization • Involves explicitly modifying guest operating system (e.g. SUSE Linux Enterprise Server 11) so that it is aware of being virtualized to allow near native performance. • Improves performance. • Lower overhead. • E.g.: Xen supports both Hardware Assisted Virtualization (HVM) and Para-Virtualization (PV). Hardware CPU Memory NIC DISK Hypervisor / VMM Virtual Server 1 Virtual Server 2 Para virtualized Guest Operating System Multiple Software Applications Para virtualized Guest Operating System Multiple Software Applications HYPERVISOR TYPE Dr. Neeraj Kumar Pandey
- 12. Bare metal Approach • Type I Hypervisor. • Runs directly on the system hardware. • May require hardware assisted virtualization technology support by the CPU. • Limited set of hardware drivers provided by the hypervisor vendor. • E.g.: Xen, VMWare ESXi Hardware Hypervisor VM Kernel Driver VM VM Hypervisor implementation approaches Dr. Neeraj Kumar Pandey
- 13. Hardware Hosted Approach • Type II Hypervisor. • Runs virtual machines on top of a host OS (windows, Unix etc.) • Relies on host OS for physical resource management. • Host operating system provides drivers for communicating with the server hardware. • E.g.: VirtualBox Host Operating System Applications Hypervisor Hypervisor implementation approaches Dr. Neeraj Kumar Pandey VM VM
- 14. Dr. Neeraj Kumar Pandey Popular hypervisors Xen KVM QEMU virtualBox VMWare
Editor's Notes
- #11: Some guest operating systems hosted in full virtualization mode, can be configured to run the Novell* Virtual Machine Drivers instead of drivers originating from the operating system. Running virtual machine drivers improves performance dramatically on guest operating systems, such as Windows XP and Windows Server 2003.
- #12: Paravirtual mode does not require the host computer to support hardware-assisted virtualization technology, but does require the guest operating system to be modified for the virtualization environment. Typically, operating systems running in paravirtual mode enjoy better performance than those requiring full virtualization mode. Operating systems currently modified to run in paravirtual mode are referred to as paravirtualized operating systems and include SUSE Linux Enterprise Server 11 and NetWare® 6.5 SP8.