SERVER VIRTUALIZATION

OUTLINEIntroductionVirtual MachineVirtualizationServer Virtualiztion

IntroductionVMM(hypervisor): a software abstraction layer between

hardware and the OS and applications running on top of it. VMM directly control hardware resource.

Virtualization first developed in 1960’s to partition large mainframe computer into several logical instances to run on single physical mainframe hardware as the host.

Virtual MachineVirtual Machine: is an abstract layer between hardware

and end-user (sometimes referred as virtual server). Virtual machines run OS. A host OS can run many virtual machine and share system hardware components such as CPUs, disk, memory, I/O among virtual servers.

Virtual MachineVirtual Machine Types: Software virtual machine (Microsoft Virtual Server 2005):

Virtual Machine

Virtual Machine Hardware virtual machine (VMWare ESX):

Virtual Machine

Virtual Machine• Virtual O/S container: host OS is partitioned into

containers or zones (Solaris Zones, BSD Jail). Each zone has its own unique process table and management tools.

Virtual Machine

VirtualizationVirtualization allows a single computer to host multiple virtual machines, each isolated from one another, with the possibility of running different OS.

VirtualiztionAdvantages: Multiple execution environment. Virtual hardware Multiple simultaneous OS. Better use of existing hardwareDisadvantages: Decrease performance. Management Interface because of several platforms into

the same environment. Increase Network complexity and Debugging time.

Server (machine, cpu) VirtualizationIs a type of virtualization (besides, Desktop virtualization,

Application virtualization (portable version)…)The ability to run an entire virtual machine, including its

own OS on another OS.

Server virtualizationServer virtualization types: Traditional architecture:

Server virtualizationEmulation: a complete hardware architecture is created in

software.The guest OS not have to be modified to run on host

architecture.Drawback: each instruction on the guest system must be

translated to be understood by the host system.

Server virtualizationBinary translation: the hypervisor manages the access of

each guest OS to the physical hardware resources.

Server virtualizationHosted OS, application – layer abstraction virtualization:

resides as an application on top of underlying OS.

Server virtualizationHardware- assisted virtualization (full virtualization, bare-

metal virtualization)

Server virtualizationVMM is directly supported by host hardware. (compared

to binary translation)

Server virtualizationParavirtualization:

Server virtualizationGuest OS includes modified(paravirtualized) I/O drivers

for the hardware. No need hypervisor instead the guest OS makes call directly to the virtualized I/O services and other operations.

Server virtualiztionHosted OS, kernel-layer abstraction (OS Containersvirtualization, Single Kernel Image (SKI))

Server virtualizationNo need hypervisor. Use containers, or sandboxes, called

chroot, to partition thehost operating system into containers or zones (e.g.Greater performance than binary translationPotential of conflict between multiple virtual machines.

ReferencesServer virtualization technology and its latest trends

(Yoshihiko Oguchi and Tetsu Yamamoto)Survey of Server virtualization (Radhwan Y Ameen and

Asmaa Y. Hano)