VirtualizationB. Ramamurthy

References

•Practical Virtualization Solutions: Virtualization from the Trenches by K. Hess and A. Newman, Prentice-Hall Inc., 2009, ISBN 13: 978-0-13-714297-2.

•P. Li. Selecting and using virtualization solutions – our experiences with VMware and Virtualbox, CCSC 2009, vol.25, no.3, Jan 2010, pp.11-17.

Moore’s law

•Intel co-founder Gordon Moore is a visionary. His prediction, popularly known as Moore's Law, states that the number of transistors on a chip will double about every two years. Intel and other semiconductor companies kept that pace for over 40 years.

•GPU’s performance and functionality have been increasing at a faster pace than Moore’s law.

Recent Advances •Multi-core: how to fully harness the power of

multi-core? Intel has been trying really hard to make us all program for multi-core!!!

•Large scale data: How to manage large scale data? Google, Yahoo, NSF and CRA have been promoting their file systems and MapReduce!!

•Parallel processing of data: How to configure clusters to process data in parallel?

•Answer: Virtualization?

Virtualization• Virtualization is creation of an alternative to

actual version of something: ▫ virtual memory (more memory than physically

available),▫ virtual time (buffering provides virtual/effective

download time that less than the actual time),▫ Virtual hardware, desktop, disk, appliances, scenes,▫ Virtual worlds

• In our context it is realizing one or more complete computer systems as guests on the base machine/operating system.

• This offers an excellent conduit for delivering the vastly underutilized power of the multi-core and other resources such as storage and devices.

Early days of VM• Technology was initially popularized in 1960’s by

IBM.• IBM 370 /VM• 1990 VMware released its virtualization product:

slow, based on x86 platform (no multi-core), expensive

• Now, we have▫ VMware suite; ▫ MS virtual PC, Hypervisor;▫ QEMU (Quick Emulator): open source▫ XEN▫ OpenVZ▫ KVM▫ VirtualBox

Types of Virtualization• Bare metal virtualization (Hypervisor?): A system

is installed directly on the hardware rather than on the host operating system▫ Difficult parts of the underlying hardware need not

be virtualized• Paravirtualization: is a virtualization technique

that presents a software interface to virtual machines that is similar but not identical to that of the underlying hardware: VMware, XEN▫ A hypervisor as a privileged level accessing the

hardware▫ On top of the hypervisor is the guest system

• Hardware-Assisted Virtualization (HVM): Zen-HVM allows interaction between paravirtualized system and the hypervisor

HostOS/GuestOS Products

•VMware server: introductory package for small environments: limited use in large environments

•Sun(now Oracle) xVM or Virtual Box: favorite among academicians as well as the authors of this text. Adjustable video memory, remote device connectivity, RDP connectivity, snappy performance, may be best hosted virtualization package.

Hypervisor Products• Hypervisor: Hypervisor is a bare metal

approach; is installed on the bare metal and then the operating systems is installed (paravirtualized); the operating system is designed as VM zero.▫Ex: VMware ESXi: 32MB footprint!▫Hardware is virtualization optimized▫VM management via Direct Console User Interface

(DCUI) at the physical console of the server system▫Vmkernel allows for remote mangement vis a set of

APIs and agents.

Hypervisor-based Products

•Citrix Xen: Earlier versions (<=3.0) were very slow. >4.0 version is very fast and the speciality is the template engine, high end virtualization

•VMware ESX/ESXi: enterprise virtualization at its best. Free product

•Microsoft Hyper-V: above products are Linux based and MS came up with Windows server version of virtualization in this product.

Emulation-based Products• Emulation refers to the capability to mimic a

particular type of hardware for an operating system regardless of the underlying host operating systems.

• Ex: Sparc version of Solaris on a non-Sparc machine.• Slow; • Examples: Bochs, QEMU, MS Virtual PC and Virtual

Server• Bochs is a free, open source Intel architecture x86b

(32-bit) emulator that runs on Unix, Linux, Windows, and Mac OS

• QEMU is another free, open source emulation program that runs on limited number of host archs.: x86, Sparcx, MIPS, PowerPC, m68K guest OS.

Emulation Products (contd.)

•MS Virtual PC is a software package from Microsoft.

•For windows env. These are good products.

Kernel-level Virtualization

•Multiple root systems•VM uses its own kernel to boot the guest

VM (called root file system)•Examples: KVM (Kernel Virtual Machine):

modified QEMU but uses virtualization processor extension

•User Mode Linux (UML) uses an executable kernel and a root file system to create a VM. UML is a part of Linux after 2.6.x kernels!

Shared kernel

•Is also called Operating system virtualization or system level virtualization, takes advantage of the unique ability of Unix and Linux to share kernel with other processes in the system.

•chroot is the command typically used•Container-based virtualization•Examples: Solaris container zones, •OpenVZ

Recommendation▫Xen▫VMware ESX▫MS Virtual PC (for Windows env.)▫For us: VMware server and Sun’s Virtual

box

Finally, there are other products besides these and many more to appear esp. with the explosion of cloud computing.